I need some important knowledge!

Could unions become corrupt inside an rbxm file? Is it safe to store unions in an rbxm file?

I don’t think so, no. I personally haven’t had issues, but I also barely use unions and stuff like that. I use Blender because unions and stuff are known for lag.

Rbxm is compatible with all the objects in the Studio so it shouldn’t be a problem.

No. All Roblox objects are designed to fit inside an RBXM file. If you’re having an issue with that it probably has to do with something that went wrong with the union itself.