Disk not shown with Enclosure Physical disks and has unusual disk ID

I have two MD1200 enclosures connected to a PERC H800 adapter (unified mode). Each has 12 SAS drives. The drives have IDs of 0:0:0 thru 0:0:11 and 0:1:0 thru 0:1:11 as expected. Except for the 4th drive in the 1st enclosure which has ID 0:7 and shows up under Physical Disks outside of the two enclosures (red arrow in image).

The drive is Ready and Spun Up with a green tick. The only available tasks are "Assign Global Hot Spare" and "Clear ...". It is the same model and revision as other drives in the enclosure. If I run reports on the enclosure, there is no 0:0:3 disk and the Slot Occupancy Report shows an empty slot.

Firmware version is 12.10.7 and drive firmware etc is latest.

I inherited the system like this and I believe it has always been like it since installation. Any thoughts on why this would happen or how to fix it?