I recently got the Onn device but was wondering how to access the files on my device to stream on the TV. When I open the media player I'm able to scroll through the folders on my phone but it says they're empty when they definitely aren't. Any ideas on what I need to do?
I don't have an Onn box, but it sounds like Android 11 security issue. Android 11 has strict file access permissions. Sometimes (but rarely) you can fix the app by granting permissions in app settings. Likely you will have to use a different app which has the necessary permissions. You could use Xplore file mangers to browse to your file and long press and select "open with" and select your media player. You could try Just Player (legacy version, not Playstore version) from here:
https://github.com/moneytoo/Player/releases