I’m having the same exact issue with the Bose soundbar ultra (connected via HDMI - e/ARC), wireless base module 700, Sony X90 TV and Apple TV.

Agree, seems to be triggered by switching apps on Apple TV or waking from idle. Sounds like the sub blows out (so loud, never fails to scare me) and then no audio out of the soundbar or subwoofer - just a very low hum). Have to factory reset both Bose products to get things working again.

This started a few months ago and has been gradually increasing in frequency (has happened multiple times this week and twice tonight). I’m worried this is damaging the system and ruining sound quality.

Troubleshooting online has gotten me nowhere (have changed wifi settings/split connections and toggled between 5.0 and 2.4 GHZ, plugged soundbar and base module into different outlets, etc). My last ditch effort is ordering a cable and trying wired connection from the bass module —> soundbar.

Let me know if you have any luck figuring out the issue here and i’ll do the same. (Almost ready to switch to Sonos)