This is a bit of a niche issue and standard use of Zwift is completely unaffected.
I’m using a Tacx Bushido which works fine. However, I like to do TrainerRoad workouts whilst on Zwift. I use the phone for TR and the PC for Zwift. The trainer is controlled via the erg setting on TR.
Importantly “controllable trainer” is unselected on the Zwift pairing screen.
This works 95% fine, but, I’m finding the resistance changes when I hit a gradient on Zwift. It becomes easier to pedal when I hit a climb.
Zwift isn’t supposed to be controlling the turbo, but something weird is happening.