I'm having problems while unwrapping uv's from some meshes I have They will either not update or become a mess if I reset them before. I'm using correct seams, I have tried appending the meshes to a new file, I've even sent the file to another PC wondering it could be a bug with my blender, but none has worked. I think it maybe has to do with my file settings, but only the meshes seem to fail, while not having overlapped topology or any other common problems. It happens with all of the separate meshes oxcept for the pigtail for some strange reason. I've also applied all transforms to all of them.
Those mentioned parts of UV are Pinned.
(vertices marked red)

Press Alt+P to Unpin and Unwrap U again :)