Miltoniopsis are fussy about growing conditions. Where and how are you trying to grow the plant?

I am growing them on a South facing windowsill in a sunny apartment (I am in the US). I have the pot behind a translucent blind (to reduce the heat from the sun which can be intense) but under a LED grow light from Orchids Limited.

Karen, to get good help you need to tell people where you are because of climate variations. You might find that your climate is too warm for Miltoniopsis, they are narrow temperature range orchids.
Here, Sydney, Australia they are rarely seen because they have to be kept warm in winter and cool in summer.
Think San Francisco rather than Southern California. It is easier to warm (and cheaper) plants up than to cool them down.

Arthur
Thanks for the input. I am in Washington DC but my orchids are kept inside in an apartment with artificial lights so I didnt think that climate would have too much of an effect. Because of the cold spring we have had this year, I very much doubt that temps have been too high and the heating in my apartment prevents it getting too low in winter.

The species ancestors of Miltoniopsis Hybrids are found in tropical Cloud forests and that is why i have had nil success with them. Tried a few times and they always slowly faded away and died.

So many orchids to grow and so many different conditions needed to keep them all happy.

What we need here is some input from growers in climates with cold winters who have had success with these orchids indoors.

Thanks again Arthur. You seem to be a font of all sorts of orchid wisdom, so it is somewhat encouraging to me find out that even you have trouble with the genus. Its a mystery to me, if pests are not the problem, why they are growing well and setting spikes but not managing to finish the job.

I do not know the answer except to tell you that I am the plant recorder at a local Orchid Society here and that in 2012 the members of that society exhibited 1880 orchids at meetings and shows.
There was 1 Miltoniopsis exhibited.
What you have to do is to set up your growing conditions to make that Genera happy. Nick did it by moving his plants to a cool-house in summer.
No one that i know has a cool house here because there is lots of stuff you can grow without going to the expense of building and running a cool house.
Now to the Bud Blast. Drafts, Gas Fires, Low humidity when flowers are about to open????? Frustrating indeed!

Still waiting on some words of wisdom from growers who have had success with Milltoniopsis