The UF2 format is a hack that can be made to generally work (e.g. it relies on things like per-block beginning and ending magic numbers to identify blocks that

The UF2 format is a hack that can be made to generally work (e.g. it relies on things like per-block beginning and ending magic numbers to identify blocks that should be written to flash, which means isn't dependent on seeing FAT table writes in a particular order). UF2 is just the file format, though. The mechanism for reading/writing UF2 files is via the emulated USB mass storage, which is fundamentally broken. The USB storage device responds to SCSI write commands with a success status, but actually throws away data, such that a successive read does not return the previously written blocks. To an OS or filesystem, that's just a failing drive. You might get lucky and things might work.