This is a known problem regarding around union bugs most of the time you would likely have to remake them again. What are you using unions for if your game has basic parts they are made out of unions you could replicate them with using a few regular parts. I recommend rebuilding the unions because that’s the only way to do so, including the useful tutorial linked above.
If this occurs with parts being corrupted you could use mesh parts, this is a common issues that developers experience. In your case I wouldn’t use a Union for something simple. If you’re making more parts out of unions try to minimize it; you’ll have to remake the part, since that seems like a simple option this is a common question that gets asked frequently. Related threads: