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Go to the online updater, hit the “Update Core Info Files”, let it finish and try again.
It’s worth noting that the Play Store version of RetroArch is a bit kneecapped by some Google restrictions, I don’t know if that’s the root of your issue but can try grabbing the apk from their website or from F-Droid.
If that doesn’t work, try Lemuroid. It’s an easier to use interface on top of a couple RetroArch cores
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Oh darn I forgot about this, yeah google screwed things up so now it’s better to download from their homepage. Though I wish they’d keep their Itch or F-droid repositories up to date, most people don’t use rss or even bookmarks these days so if anything’s updated nobody knows.