Yes, I (normally) use a Jolla 1, and now that you mentioned it - I used BTRFS balancing a day ago... I already rebooted several times, but it didn't help u_u

Add-On: unfortunately, I didn't backup anything this time... My journalctl only warned bc of some ioctl kernel error (512), but that might be too far off the symptomatic problem. Maybe when I use one of the old backups... But I don't know what I might probably lose, so I'm still hesistating.