I have no idea...I am adding a post that has troubleshooting guidelines. I have looked and looked and there are none that apply to mixes...so some of these don't apply since they talk about measuring ingredients. The consistent thing seems to be the heat is uneven or too high or too low. Read it and see what you think. c

Here is a link that might be useful: troubleshooting cake baking

A few questions:

Were the tests done with only 1 rack in the oven? Was there, perhaps a rack above the cake?

On which rung was the oven rack? Where in the oven?

You keep mentioning the Taylor thermometer so I'm confused. Did you adjust oven temp to the thermometer for the tests or did you just use the digital readout for the oven on each setting?

Cracking is a sign of overbaking -- either too long or too hot. Depressions can be caused by the way batter is added to pan, or if not leveled after adding, or they can be caused by under-beating.

But they should not be there since the mixes should be more or less self-adjusting. They have a ton of leavening in those mixes.

The most helpful thing at this point would be to see pix. Did you take any by chance?

Still hard to tell what's going on.

based on what I read to now, I think a call to service will result in nothing but frustration for you.

There does not seem to be anything technically wrong with the oven. The fans work, the heating elements work, computer works, ect....

Now , I totally get that it doesn't perform in this test, but they are going to say it's operator error or something wrongs with the cake product. That's reasonable from their perspective if nothing is malfunctioning on the oven.

The grey area is that an oven (especially one costing $4k + ) should be able to bake something a ubiquitous as a box cake mix reasonably well. That said, I've seen these things turn out less than perfect in budget Hotpoint ranges as well as big $$$ Gaggenau and Miele ovens. My experience tells me it has more to do with the baker than it does the oven. Remember it's a tool, and if it is functioning properly, it's up to the user to be able to use it to produce the desired results.

Besides, isn't that what frosting and sprinkles are for - to cover up the ugly tops of cakes?

I don't have a specific answer to your oven issue, but as a baker, I was struck by your use of "shiny pans" for your cakes. Shiny pans are not a good choice for cake baking. Cook's Illustrated has numerous times done testing of baking pans of various shapes. In one test they wrote, "We've learned over the years that pale and shiny finishes lack the superior heat absorption of darker finishes, resulting in spotty browning. Dark-colored surfaces absorb heat in the oven; bright surfaces do, too, but they also reflect it. So we dismissed the light-colored pans from our lineup early on." At another test they said, "The dark coatings on these pans promoted better browning than shiny surfaces and yielded more attractive cakes." Still another test resulted in "pallid crusts" from shiny pans. Depending upon what they were cooking (round cakes, cornbreads, brownies, etc.), their winners for baking were either a pyrex pan, the Chicago Metallic round nonstick cakepan (very dark), or the Williams Sonoma Goldtouch square cake pan.

Sorry I don't have a solution for you, but perhaps changing your cake pans would do away with the depression you found in each of your tests. Also, I would think the oven rack location has had an effect on your baking - too low, and the bottom of the cake cooks before the middle & top, which may result in a depression due to the differences in temperatures and textures (hot firm/crusty on bottom of cake while top of cake is still cool/wet).

All true antss and likely you're correct. But this is not our mother's oven and as much as I love mine I do feel it's over-engineered.

Another culprit is the woefully inadequate user manual which uses inaccurate cooking terms and has contradictory information.

They could do way more hand-holding, provide video tutorials on the website with downloadable recipes that apply to each of the cooking modes -- so it becomes clear how and why each mode works. F.ex. If you use surround for a layer cake there could be a problem -- you're pretty much broiling the top -- though it's good for Shepherd's Pie or baked ziti when you do want top browning etc.

It's shameful that an owner needs to come here for basic user information about a $4K appliance. The manufacturer is functioning like it's 1985 in terms of the consumer but can get micro data from the oven like how many hours it's been used.

Thanks to all of you, really.....I appreciate the time you've spent with me, and I wish I could send you all a layer of the cakes which are carefully wrapped and in my freezer.
Just to answer a few of the questions you posed -- I tried to be as consistent in mixing and baking with each batch. Temps used were according to the digital readout, the thermometer concurred that the oven was pretty close to accurate per setting. Batter was added the same way I've been doing for the last 30 years and each pan was weighed for equal layers. The pans were lined with parchment and they are from Wilton. I've used them a million times and there was no problem with the one layer of each cake experiment that didn't have the depression....remember in each test only ONE layer of the two showed the depression. According to Miele's directions, I used the first rack from the bottom according to their miserable manual's instructions, and I have a feeling as mentioned above that might have been the factor. Normally I bake them in the middle of the oven. Funny though how it didn't matter if I used convection or non the depression showed. I thought with convection you could bake anything anywhere. All three racks were in the oven during baking. I did take pictures but it's hard to see the depressions. Originally I was testing to see if the cake layers would rise
evenly, (they more or less did) unlike that challah bread I wrote about originally. So yes, we have no real answers!

Sounds to me like the oven is ok and it's just a question of adjustments. I have Wilton pans and they don't cause a problem. Without seeing photos I couldn't comment further on the issues around the bread or the cake layers.

I'll give you a rundown of how I use mine and what I do/don't do. Perhaps trailrunner and loves2cook4six also will chime in here as they are both bakers and have the same oven. All this said with the caveat that mine is an older vintage, non-self-cleaning and has the grease screen in back that needs to be removed for the baking modes to work properly.

FWIW I find the masterchef settings useless and guaranteed to overcook anything. I ignore them.

I preheat 30 minutes. With stone, 45-60 mins.

Convection Bake: For single rack I use 2nd rung. For cakes (including angel food), cupcakes any delicate pastry (meringue) and any time I'm doing multiple racks. Have done 3 racks of cookies and 6 pies (which took a bit longer) with success. If not doing multiple racks, I remove all but rack I'm using and remove the drip pan. I don't ever leave a rack in over anything I'm baking. Also sweet or higher-fat bread, anything with a soft crust. Have found this to be even, gentle heat.

Intensive: Pies, crusty yeast breads, cobblers -- anything that needs bottom action or a heat boost. Pizzas, naan, calzone with the stone on rack using bottom rung. Heaviest batter breads that might not cook through easily.

Surround: I don't use this much because it essentially broils and bakes at the same time. I adjust rack low to high depending on how much browning is needed. Good for things like Shepherd's pie, baked ziti, gratins, casseroles, stuff with toppings like cheese, bechamel or streusel.

Bake: I think of this as dumb-bake. My setting is 15 degrees slow so I adjust it. Any time I want a slightly moister baked product or don't need the convection I use this setting since the air circulation will make things drier and crisper. All reheating. I don't find this slower than convection, just has different use.

I'm an oven cook and have really come to depend on mine. For savories, autoroast rocks and so does the rotisserie. I like the probe and while it requires a rough calculation of cooking time (another unhelpful aspect) the countdown and alert are great.

Again, disclaimer: There are few absolutes and my ideas on how to use "European convection" are based on English oven website I stumbled across which actually made some sense of it. Miele needs to do a much better job.