Problems with trainer reconnection after reentering the app

My setup:
Google Pixel 2 (with Android 9) + Wahoo Kickr Core. Connecting with BT.

What was the problem:
Updated the app today. During training I had to quickly open another app. Not a big deal, because before update I was able to reconnect trainer fast after switching back to zwift app. But this time when I switched to zwift I failed to do it - trainer was showed as “connected” but with “no signal”. Waited for a minute, but nothing changed. (btw it was quite frustraiting to not finish a training after stopping at 80% of SST long).
I ended the ride. Then tried to connect again - no success, app didn’t even see a trainer. Turned off trainer, then turned it on - no success again. Only after fully closing zwift app (swiping it away from opened apps list) and opening it again I managed to successfully connect with my trainer again.

Reproducing the bug:
After that I tried to reproduce the bug, and it reproduces consistently.
I did it on a starting screen and during the ride.

On a starting screen:

  1. open app, find a trainer
  2. switch to another app
  3. swith back to zwift
  4. most of the time after that I can’t see the trainer at all, no matter how long I wait. So the only option to connect it again was to fully close zwift app. For some reasons sometimes, I think it was 2 of ~10 attempts, I still had a trainer connected after switching to zwift and it was ok. Also in 1 attempt I got the same affect as in my training - trainer was showed as “connected” but with “no signal”.

During ride:

  1. open app, find a trainer
  2. Start a ride as usual
  3. switch to another app
  4. swith back to zwift
  5. 1 of 3 attempts was ok and I had a signal and trainer was working fine. But 2 of 3 times I got the same, “connected” but with “no signal”. Reconnection was possible only after fully closing the app.

P.S. Still not sure why I have to lose connection at all while switching to another app, because zwift still runs in background. Maybe problem is in keeping BT connecton for apps in background, I can understand why such things can be a problem, but any info about that would be useful.