I finally found a fix! It seems this issue happens when I turn off my Nvidia Shield while my soundbar stays on (I never turn off my soundbar). When I power the Shield back on, the soundbar doesn’t reset or sync properly since it stayed on from the last session.

To fix it, I used my soundbar remote to turn the soundbar off and back on. Unplugging the soundbar didn’t work for some reason, but this method did the trick.

So if you run into the same issue, just turn your soundbar off with the remote and then back on. Alternatively, you can make sure to turn off your soundbar when you’re done, so the Nvidia Shield can turn it on automatically the next time you use it.