WoW Companion App - Only on WiFi?

So, as the title implies, my WoW Companion App will only work while connected to the WiFi - it won't work just on mobile data.

I saw a suggestion that there is an app setting that had to do with mobile data usage, but I couldn't find anything on my phone that is related to the companion app (though I could see it for other apps).

For the record, I am on T-mobile, and am using a Samsung Galaxy Note9.

Thank you much!