Thanks, Hotel!
Rotation isn't working at all through RCS. They activate just fine for translation, but only the reaction wheels are responding to QEWSAD keys.
I tried swapping to the Vernor engines with the same results, except now the ones positioned for forward movement are activating with the throttle, despite it being disabled.
I did notice that the pitch/roll/yaw toggles are cycling between on and off several times a second.