I'm about 5 years and 10K Zwift miles into using a Wahoo Kickr SNAP wheel-on trainer, no problems.
A few times over the years, always after a Zwift update, I'd have "reverse" gradient applied - going up a hill on Zwift would feel easy, down would be hard. I found that restarting Zwift usually cured the problem (I run Zwift on Apple TV) but at least once there was another Zwift update which cured it when restart did not.