Using Blender 2.8, I have run in this issue with several models, so I am guessing it's something trivial and common.
For example, if I try and enlarge the tmd turrets of the Cybran battleship, and rearrange the barrels and muzzles from their current vertical positioning to a horizontal one, I can export the model without errors but as soon as i cheat spawn it in game, the game will freeze.
Now, i know it's a mesh issue because it does not freeze if I am fully zoomed out, but as soon as i start zooming in (the model turns from an icon to a model), nope, freeze.
I have tried merging vertices by distance of the entire mesh (seem to have read somewhere about that), which step am I missing??
Seeing as how I have ran at the same exact issue on several units I tried editing, i am fairly certain it's a very common thing.
But what is it, what am I forgetting?
This thing pretty much kills my every attempt to create something And it's annoying as fuck, because I just know it's something stupid and minor and solvable in 3 clicks