On a hunch I fired up RTSS and limited Gehn Shard's UruExplorer.exe to 90 FPS; seems to have fixed it. Maybe.
Or maybe just rebooting the game fixed it... dunno. But the dark corners of my memory whispered something about Uru not liking high framerates. Anywho... never mind.
After activating the correct sequence of floor lights for the "dark path" puzzle in Kadish Tolesa, my character gets "stuck" on/in the floor (where the lights and shadows are), and the character model switches to the falling animation (one leg down, one up, arms flailing) despite being frozen in ...