Did you go through the Add Surrounds process in the soundbar settings, where you select which is left and which is right? Just checking.

If so then I would suggest you force quit the app, and turn off the router and speakers at the wall. Wait five mins, then fully boot up the router, followed by the soundbar and then other speakers, letting each speaker go to white light before moving to the next.

Then re-open the app and see if it’s all there.

Also make sure the app is updated, and also settings - general settings - system updates - check for updates.

Could this be related to the garbled sound you were experiencing recently? What did you do to resolve that issue?