Thank you for your post!
If your are still using the "Classic Theme" on your layout, I'd recommend moving off of it to something like "Minimalist". Newer versions do run into strange issues as the Classic Theme was deprecated and removed.
If not that, are you using a standard font?
Does changing the font affect this?
Appreciated TSPigeon, as always.
We'll let you know what we find out!
In our case, changing the font made the problem go away. Geneva to Tahoma.
Thanks for pointing us in the right direction, TS Pigeon!
ericjungemann: Thank you for the tip to change the font, it solved our dropdown issue. Except in our case, Arial Bold made the dropdown a "dropover" - covering the field and confusing users. Removing the Bold style reverted the dropdown to the original position BELOW the field. Not a huge deal, but a puzzling nuisance nevertheless.