I used the subdivision surface and shrinkwrap modifiers to create a retopologized surface.
To apply the shrinkwrap modifier properly, I applied the both modifiers and unsubdivided with the multiresolution modifier. However, a hole showed up.
It was a dimple with a single vertex that somehow ended up inside.
I can’t get the grab tool in sculpt mode to lock onto the vertex and in edit mode (probably because I’m using multiresolution), the vertex doesn’t show up.
I tried using all the red tools in sculpt mode already, but they don’t work either. Are there any other solutions I’m missing?
your problem is most most likely inverted normals, which you can check with Viewport Overlays > Face Orientation, and fix with Mesh > Normals > Flip