Alright, after some more tinkering around, I've discovered something else.

If I try to run the level now, there are a bunch of models and entities that show fine in preview mode but then do not load up in Run mode.

If I delete all the content of my level at one time and try to compile, of course it won't, but then when I hit "undo" and it all comes back, if I then compile again and "Run", DIFFERENT MODELS AND ENTITIES DISAPPEAR than the ones that disappeared before removing all content and then undoing.

Why would models and entities that had disappeared before suddenly appear, and models and entities that were there before suddenly disappear?

I'm thinking that there's nothing wrong with my models and entities themselves, but rather there may be an issue either with numbering system of the models and entities in my level (removing and "undoing" (re-adding) may change their "block number" somehow?), and/or 3DGS can't handle the number of models and entities I have in my level.

Can anyone else confirm or deny these theories? Is there some way I can force 3DGS/WED to re-number all the blocks and entities in my level?