edit. So if Tab was still mapped to the FullScreenAutoHide-- that means you never successfully made the assignment for Tab=Fullscreen… hmm… So Tab works fine when you’ve already entered full screen; it hides the tools panels, right?
Is it only Tab=Fullscreen that is broken? That is, can you map Tab to something else like zoom or increase brush size, and does that work?
If nothing else, try remapping FullScreenAutoHide to something else, and then edit the file as I mentioned before and just set it. Let’s see if that at least is a work around and let us know where the error lies (possibly during assignment).