I have two models that fit together set up in the scene.

I've made some holes in the first model already without much issue.

I wanted to make sure the holes would line up when I put the two pieces together so I lined them up in the scene.

But when I go to dig a hole in the 2nd model, it just mysteriously teleports out of the bounds.

The hole DOES get dug, but of course I don't want to have to re-align it for every single hole I want to make, that's absolutely awful.

There's no way that's not a bug, right? Why is it doing that? I would love a fix for this! Otherwise I'd love an alternative recommendation to chitubox because honestly, when it's not crashing, it's doing crazy stuff like this. 

Uploading the video threw an error but still seems to think it succeeded so here's a link just in case:
https://drive.google.com/file/d/1d7WReHmpq7wDW26Kni9Y97Z3ApqYPEhG/view?usp=sharing

Thanks in advance!