I have just had a reply from Zwift support regarding the proble I have with Bluetooth and resistance
Hi Chris,
Thanks for contacting Zwift!
I'm sorry to hear that you're having problems with resistance dropouts or disconnects on your Kickr Core in Zwift.
Some Zwift members are experiencing resistance issues on their Kickr type smart trainers when pairing via bluetooth (BLE). It appears that you've encountered this game bug.
Some users have tried these steps and claim it works (but they have to do it each time):
1. Power off (unplug) KICKR, leave unplugged for 30 seconds, then turn it back on.
2. Launch Wahoo Fitness app and connect KICKR.
3. Run KICKR on Wahoo Fitness app.
4. Check if SIM mode is enabled. If not, enable it.
This article explains the different modes on your trainer.
5. Disconnect KICKR from Wahoo Fitness app, but leave plugged in/on.
6. Launch Zwift and pair KICKR within the game.
7. Try a ride and let me know if that helps.
I have just tried this and it stay connected when I click to ride ,just got to try it tomorrow and do a ride