It’s occasionally possible that the ‘other’ TV HDMI connected devices, with HDMI-CEC enabled, are stealing ‘focus’ away from the Sonos Home Theatre device causing such audio interruptions. So perhaps consider this suggestion below...

Power off both the TV and the connected Sonos Home Theatre product and then disconnect the ‘other’ HDMI devices from the TV. You can then power the TV and HT product back on.

Through continued use, see if the audio dropout problem disappears, if not, then check for any available TV firmware updates at the TV manufacturers website, which may (hopefully) fix the issue. If no update is available, then I would do these two things...

1. Contact the TV manufacturers support desk to see if they are aware of the issue and see if a fix is perhaps pending. 
2. Submit a Sonos Diagnostic and post it’s reference back here and then contact/chat to Sonos Support via this LINK.

Assuming that there are no audio dropouts after the power-cycling of the TV etc; next reconnect one of the removed devices back to the TV and see if (over a period of time/testing) the audio dropouts begin to re-occur. If so, switch off HDMI-CEC on that reconnected device.

Continue the process of reconnecting/testing the remaining TV devices to see if any cause the audio dropouts and if necessary, disable their HDMI-CEC feature. It’s obviously best to do this one device at a time and some patience maybe necessary to test each reconnected device.

Note: Some TV connected devices may not have an option to switch-off HDMI-CEC, in which case it might be advisable to insert a CEC-LESS adapter between the device and the TV. 

An ‘example’of such adapters are shown here in this LINK

Hope the above suggestion and information assists to resolve the issue.