The 1.8.3.0 patch ruined many hours of work on converted aircraft. Here’s a workaround to get them flying again.
Those of you who are able to edit .mdl files in ModelConverterX can remove all mouse rectangle assignments from the interior model. Use the Object Heirarchy view, highlight all of the elements, and set the Mouse Rectangle field to None. Then export it back out, delete any related CVT folder that may be present, and you should be good to go.
I just tested this with about 8 different aircraft and all work again!
Make sure to save a copy of the mdl with the click spots still in place so that you can swap back to it if they hopefully fix what they screwed up.