Ruida controller stopped cooperating with rotary

I have a ruida rdlc320a controller and a chuck-style rotary attachment connected to my Y axis. I've used this many times with no problems. I just go into LaserWorks, enable rotary, set the diameter, and let it burn.

But yesterday I put a cup on the rotary, set the dia to 82mm, and drew the bounds with the laser to make sure the handle of the cup didn't hit something when it rotated around. Well, it collided with the laser head.

I double checked my measurements and the job should have fit fine... So I drew a 25mm square and let the laser draw those bounds. The X axis was perfect. The Y axis drew a little over 50mm.

The Circle Pulse setting has always been 20000 for me. So I clicked Test for the rotary output and it spun the cup just over 2 full rotations. Which makes sense if it is drawing 25mm as slightly over 50. So I changed the Circle Pulse to 10000 just to see what happens. Nothing changed -- still a little over 2 rotations.

So I unplugged the rotary and plugged in the Y gantry. I calibrated both axes (both were fine). Went back to the rotary. Still wrong.

I'm not sure what went wrong out of the blue like this, and I have no idea what I can do to fix it. What should I check next?