I’m trying to tweak a model, but when i grab a vertex to move or edge slide, the G key is making the vert, or another, jump wildly to what appears to be the mirror position;
It might be a good idea not to crop the screenshots so at least some settings in the UI could be visible. Proportional editing or mesh symmetry settings might have something to do with this.
Another guess:
The head has a mirror modifier and only exist on the left part and the lash is with shrinkwrap but only on the right and maybe also symmetry is enabled ??
no prop used. dunno what the issue actually was but the lashes were a U-shaped loop to give a double thickness i guess, and i’d cut them down to one loop. when i looked again in isolation there was a slight lip of faces left, so i deleted those too and it solved the issue. no idea why.