Hello, according to your description:
- Check your USB drive's partition and file system. When connecting an external storage device to iPad OS 14, it must have only a single data partition and it must be formatted as FAT, FAT32, exFAT or APFS.
- Update your iPad. You can check whether it needs a software update in the System Settings.
If your encrypted USB drive is an APFS formatted drive, you must update to iPad OS 16 and the drive must not be partitioned into more than one partition.
If these don't work, you will need to seek assistance from the manufacturer of the encrypted USB drive.
