I have the same issue on mine. Not all the time, but it comes now and then. Multiple branded SD cards, including Samsung Evo cards, and SanDisk extreme cards. Doesn't matter if it's a cheaper slower card or super fast SD either. The error pops up. No issues with anything else using the card on the phone. Sometimes I'll notice pictures I took are in internal memory instead of the SD card, meaning it's not recognized for a while. Came from an s8, using the same card and no issues..
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