I think our #Brother printer is messing up my FAT32 flash drive. Several time I formatted it, but then after using it on this printer there would be issues, sometimes my #Debian laptop refused to mount and read, sometime #Windows failed to detect filesystem or failed to read/write files properly. But the thing to to keep it universal for Windows, #Linux, #BSD and the printer, FAT32 seems to be the only choice. I am gonna use another flash drive for now just to make sure there is no malfunction in the thumb driver itself.