Weird, it shouldn't have had room to have 'slipped'. I suppose that bent end on that hidden side might have broken off or straightened out somehow. I'd try pushing the tab that you can see as far ccw into the ratchet as I could while jiggling the anvil assembly with something, maybe by putting an extension on it, to see if you can convince the hiding side to peek out of there. Might help to shoot a bunch of penetrant up in there, or dunk the whole head into some ATF or the like before doing so.
Barring that might have to locate a rebuild kit that contains a new anvil and get destructive to get the old one out.