I recently bought a generic USB 3.0 to M.2 adapter. It has a JMicron JMS567 chipset that very recently had a quirk added to the Linux kernel that fixes UAS support. Even with this patch, smartctl returns:
/dev/sdb: Unknown USB bridge [0x152d:0x0578 (0x508)]
Please specify device type with the -d option.
This can be fixed by telling smartctl that it is a SCSI to ATA Translation (SAT) device:
smartctl -a /dev/sdb -d sat