Erg mode doesn't work through the companion app. But does work when connected directly

My normal setup that I use 99% of the time is the companion app on my iPhone, connected to my Tacx Neo, and my wahoo tickr. Then Zwift running on my PC.

I use this all the time, for months, no issue.

Tonight, I noticed that during my workout, ERG mode wasn’t controlling my resistance. I think maybe it would try, but the watts were all over the place.

I tried:
Turning ERG mode on/off,
Restarting the ride
Trying a different workout
restarting Zwift
Tryin different gears
Restarting the iPhone/Companion app
Reconnecting my devices
Updating the Neo
Restarting the Neo
Restarting WIFI router
Disabling bluetooth on everything but my iPhone

Finally, I decided to just try running Zwift on my phone, and then ERG mode was working. That works as a temporary solution, but I would really like to get back to using my PC. Anything else I can try?