There is a very strange way Nomad works in a particular area.
I masked and hid the majority of a character so I could isolate the teeth. Then I masked each individual tooth and split them from the body.
After that, I should’ve been able to go back to the body mesh, “unhide” the previously masked parts to reveal the whole body.
Instead the body was just GONE. Why? I didn’t clear the mask, I didn’t delete hidden (is that even possible in Nomad?), I just hid a part of a mesh. But at some point Nomad just said, “ah we don’t need that whole other giant thing you’ve been working on for days.”
EDIT: fortunately digging around in the project folder, there was one saved file from 2:04am that was still untouched. Strange it didn’t show up in my Nomad:data:projects folder but it did show up in my Nomad:projects folder.