Hey stradibarrius,
this may be caused by exFAT Filesystem nowadays found on practically every USB drive bigger than 32 GB. Because of the age of the underlying Operating System in the Onefinity Controller, support for exFAT may not be available (it would have to be installed by a package). If your flash drive is not recognized by Onefinity Controller, you have to reformat the flash drive using NTFS or FAT32 instead.
exFat would be supported natively with Linux kernel 5.4 but I have no idea if or when Onefinity will switch to a newer version of the underlying OS.