"No signal" when joining an Event with Companion app running

Zwift Companion via Android
Zwift Game via PC

I can free ride with the ZC app no problem, all primary devices connect on the pairing screen via Ant+, PWR, F-EC trainer, Cad and HR. I have a Sterzo Smart connected via Bluetooth. However as soon as join an event, and I’m warming up in the pen, all data stops, my avatar stops pedalling and the pairing screen shows “No Signal” for all devices. It refuses to find or connect to anything.

My last session yesterday consisted of a 55 minute free ride - badge collecting - with an Academy group ride scheduled for afterwards. I ended up quitting the group ride because of no connectivity and zero progress with the other participants.

If I don’t have the Companion app running none of this happens, I can free ride and complete events without problem. First time this occured was October 1st.