...installed the JMS Firmware upgrade to be on the safe side and it seems I did not have the current version. See output of smartctl -a /dev/sdb1 below:
=== START OF INFORMATION SECTION ===
User Capacity: 4,000,787,030,016 bytes [4.00 TB]
Logical block size: 512 bytes
Physical block size: 4096 bytes
LU is fully provisioned
Logical Unit id: 0x3001234567891234
Serial number: 0123456789ABCDEF
Device type: disk
Local Time is: Tue Jan 29 11:45:38 2019 UTC
SMART support is: Unavailable - device lacks SMART capability.
Serial Number has changed, still no luck getting through to the HDD...
EDIT: solved it!
smartctl -a /dev/sdb1
gives the result pf the JMicron bridge,
smartctl -a /dev/sdb1 -d sat
gives the results of the HDD.