I have an issue with Automatic Weights with my human character, it fails. So I'm trying to weight paint manually, however strange things happen:
There's no weight painted under the neck. You don't have to care about other vertex groups, I already checked many times, there's no weight under the neck.
However when I rotate the neck bone, vertices at the end of the mesh still affecting on neck/head bones even it is 0 weighted:
I don't know why this happens, those vertices doesn't have any vertex group, all 0 weight painted.
What should I check to fix this issue? Any advice will very appreciate it!