On-Demand combat speed? It has ceased to function for me.

I noticed recently that my ability to hold the spacebar to speed up combat has... just... stopped? Completely stopped. I can turn on combat speed ups, and that works, but there's no difference now between having it off and having it on demand. which I don't like, because I don't always want combat to happen at turbo boosted magic carpet speeds.

Is there a way to fix this? I've looked in my settings and online, but it's such a minimal problem that I haven't even been able to find anyone else who even has the same problem as me.

Edit: I have tried uninstalling and reinstalling. i've tried with and without mods. I've verified files and everything. I also checked my keyboard, tried different characters and saves at different points in the game. Shit just don't work no more.

Secondary Edit: I asked on the steam forums and apparently they changed the keybind for it in the latest patch.