Resistance does not match downhill, flat road or uphill

Hi there I am experiencing issues with Zwift on my iMac or maybe my hometrainer a tacx flux. When I drive uphill I do not encounter resistance, almost the opposite, and watts fall. It happens also on flat stretches that I get the feeling of running uphill and watts rising. When I then drive downhill, it varies whether the resistance feels like downhill or uphill. I am connected to my iMac via the Bluetooth connection in the PC, and the trainer is close to the computer. Any idea of ​​what might be wrong?

I get the same issue. Can’t get hold of the zwift team to fix it

The same issue. It happens not all the time but occacionally. MacBook Pro and Tacx Flux connected via BT.