A possibility to consider is that the odor is coming from the water supply, perhaps caused by a recent change in water chemistry.

Or maybe the new machine rinses much more thoroughly and there isn't any of the detergent and Unstoppables scent remaining (those are added up-front to the wash period, yes?). You could try adding the Unstoppables to the final rinse but that could run into the issue of that phase of the cycle not being long enough for them to fully dissolve. Or try a liquid fabric softener in the machine's dispenser, which injects into the final rinse.

Hot Water Odor

Are your clothes by any chance made with wicking polyester fabric?

What model Maytag do you have?

Add a few drops of Lemon essential oil to your liquid detergent. it helps cut the oil out of the clothes. I have horses, chickens, cats and dogs, so I wash a lot of smelly stuff! Honestly, though, out in the woods on a horse, it is insulting to my nose to smell people’s laundry scents from about a quarter mile!!

This is a timely post for me! This past week I started adding 1/2 cup of 20 Mule Team Borax to each load of laundry. Everything seems brighter and has a very clean, fresh scent. It is a color booster and can be added to whites, colors, everything. an added bonus is that it can also be used for a wide variety of other household jobs.

The OP said borax has been tried to no good effect.

I switched to powder detergent (real powder, not the pods with powder in them) with my front loader and I'll never go back to liquid. No more problems with the musty smell in the machine or clothing that doesn't smell clean. I've had good results with a variety of powder detergents. I put the detergent in the washer with the clothing instead of the detergent cup.

I know you said you’ve tried a cleaning cycle with vinegar, but I’d also recommend adding a half cup of plain white vinegar to each load, plus a couple tablespoons of detergent (I like biokleen).

I agree with with what ci_lantro said and like to add my elderly mom has a Whirlpool which is very similar to your Maytag and I found the normal cycle doesn't do a good job getting her laundry clean or fresh because of the low water level and cool wash temp. Does your machine have a quick or rapid wash cycle? That uses a good amount of water and does a pretty good job of cleaning when it's set to heavy soil and an extra rinse is added. I also suggest using no more than 2 tablespoons of detergent. If you really want to boost cleaning and freshness, set the washer to hot in the rapid wash cycle. I also find less is more when it comes to additives...Keep your routine simple.

OK, I'll say it -- more water does not get your clothes cleaner. Actually, multiple washes with less water does a better job than one wash with more water. It may seem counter-intuitive, but it's basic physics. Moving on.....

I too wonder if it's just about the machine actually doing a better rinse - in my opinion, clothes should not be scented when they come out of the wash, so if they are, their not getting cleaned or rinsed properly. (As an aside, too much detergent or additives can build up and damage the machine.) I recommend using some Affresh dishwasher cleaner (my preferred brand, but there are others) and check your connections to make sure the water is fully draining and there isn't anything partially occluding the outflow. If your machine has a door in the front to check the drain trap, check that too.

I want to echo what Ci_lantro said - it’s all about the water temperature. It’s possible your previous machine had an “energy-hogging” built-in internal water heater, and your new machine does not. Add to that issue that it’s December and the incoming water temperature will be cold. It could be that your washer‘s first influx of water may be ice cold water that has been sitting in the pipes. The later water that is hot from your home’s water heater won’t be able to overcome that, especially if the washer has no built-in internal water heater. So you are washing in cold water or lukewarm despite your intention not to, and having the problems associated with consistent cold-water washes.

Short of returning this washer for a different one that does have an internal water heater, one trick is to run the hot water at the sink that is nearest your washing machine. Run it until you feel the hot hot water. Then turn on your washer.

We get an issue with funky smelling clothing... not mine, but the rest of my family. I’ve been able to narrow it down to clothing with polyester in it. The reason mine doesn’t stink is because I have an allergy to polyester and I only wear natural fabrics. Anyways, to get rid of the funk smell out of the clothing I wash it periodically with the normal amount of detergent I use, plus a few drops of tea tree oil, and I wash it on either warm or hot depending on the type of clothing. After that first wash it smells too much of tea tree oil for my taste, so I run it through another normal wash with very little detergent. After it’s done with that the clothings smells perfectly fresh and clean, I seem to need to do it every few months or so. Also, be sure you’re thoroughly cleaning out the inside of your washing machine on a regular basis, including the seals and inside of the door. Anyways, I wasn’t able to get rid of the funk with just hot water or a change in detergent or vinegar or bleach or anything like that... but the tea tree oil does the trick for us!

Synthetic fabrics can hold onto soils which causes odors. Synthetics don't like water and expecially don't like cold or even cool. The fibers will constrict in less than very warm which prevents solution from getting into the deep fibers to release soils. Synthetics require very warm to hot to relax fibers allowing solution in and allow soils to be broken down and flushed out. Synthetics also require more space to move and more water... so never overload.

Another thing...clothing that is heavily soiled at least enough to change the water to a yucky color will benefit from at least a quick cool prewash otherwise all that mucky water will allow some soils to remain.

Workout clothing seems to be a problem for some...first it's usually synthetics and full of sweat. The sweat infuses the wash water and some remains and allows odors to build.

Hot or very warm water

A good detergent

Prewash heavily or moderately soiled garments.

And don't overload...allow extra room for the garments to move in the water.

Try hot water with Larsi’s Stink Bombs — Tide Sport Pods with Febreeze — that’s the only thing that works in my husband’s laundry because he always has synthetic workout gear of some ilk in every load. Use it in addition to your regular detergent. https://smile.amazon.com/Tide-Febreze-Defense-Detergent-Packaging/dp/B01BZQJLFW

I doubt it is water related since it didn’t occur with your LG. However the issue related to cycles and lower water temperature is a possibility. I would recommend Tide Uktra Stain Release Free which is sold at Target. Also, try ammonia in each wash (except when using bleach) to help remove doors and build up of gunk in your clothes and machine. About 1C will do. Make sure your clothes are fully dried as well.

Daryl, a year later -- what did you do? Did you find success? Please share.

Now that I read this a year later I think the issue is the Maytag is a poor rinser compared to your old LG. If you are using the normal cycle, it doesn't spin between the two default rinses. Try using a different cycle along with a high quality powder detergent such as Tide and add an extra rinse. It might take a few wash cycles for your laundry and washer to smell fresher, but try this routine for a month and see if you get satisfactory results. Then let us know.

I wonder if it was the Persil? I do recall a lot of people complaining of the smell after clothes would sit for a while when using Persil for an extended period?