If you spam it enough, the camera on the main/active window will spin around your toon slowly, as if it doesn't know which direction it is supposed to orient to/from.

But just clicking anywhere, to actually click to move via the mouse on the active toon fixes this easily. I don't get the bug often, but saw a few posts in relation to it, that was given as a solution, and when the bug surfaced it worked to remedy it for my kittens.