Couple of things, but no real answer, I’m afraid.

First, the app is only a remote control / window into what is actually happening on the computers in the Sonos devices. There is no reason to worry about deleting the app, and reinstalling it, as long as you use the ‘connect to existing system’ option, when you install. If there was something ‘broken’ in the download/install, a fresh copy makes sense. 

I don’t have this issue with my headphones, but given that you already have other speakers, there is no reason why a factory reset of just your Sonos Ace should be an issue…just don’t do any factory reset of your Home Theater speakers….although I’d sure be tempted to try a power cycle (not a factory reset!) of the Arc itself.

Finally, I would call Sonos Support directly to discuss it.

When you speak directly to the phone folks, they have tools at their disposal that will allow them to give you advice specific to your network and Sonos system.

I’ve hit a couple glitches with my Ace too, factory resetting them along with rebooting the controller’s device has usually got me to the point every thing works.

Removing/reinstalling of Force-Stopping the app may help too but for me it is easier to just reboot the controller’s device.Do check the system and Ace to make sure both are fully updated.