When in the sensor pairing screen when you pedal does it show any numbers besides 0?
Are you running Zwift on your iPhone or another device? Cause if the sensors are connected to your iPhone (Bluetooth) and you are running Zwift on AppleTV you wouldn’t be able to have 2 concurrent Bluetooth syncs. You can only have 1 active Bluetooth stream per sensor, not sure how you connect them to your head unit but unless it’s ANT+ that may be the issue.
I don’t have a non-supported trainer so not sure if I can help out anymore but it sounds like there is some interference prevent Zwift from receiving the data from those sensors.
Thanks for the responses. I am running Bluetooth from speed and cadence sensors to my iPhone. I have signed up to Zwift and currently on the 7 day trial period but my ‘flag’ is still greyed out - not sure if this is relevant or not ?