Android Musescore does not play Musescore4 Files

Back when I was using MuseScore3, I could download .mscz files to my android phone and play them with the Android MuseScore app. In Android MuseScore, I would go to Songbook, press + at the top, find a file on my phone and click on it. After that the file was always available to play in Songbook.

Musescore4 files act like they are loading as the Musescore3 files do but they never start. The yare "available in Songbook but NOT under their name but under a ten-digit number. If I try to play it, I get nothing but a blank screen

If this is the wrong place to report this, please let me know what the right place is. Thanks for your help.