EX2 Degraded, red LED but GOOD?

I have a EX2 Ultra with 12TB in RAID 1, I purchased prebuilt over 3 years ago.

Everything was good but a little slow before upgrading to OS5. After upgrading to OS5 I get that the volume is degraded and a red LED on Disk 2.

S.M.A.R.T. Data shows both disks as good.
Running Scan Disk gives result of “The Volume has been successfully scanned. No errors found.”

Running any of the System Diagnostic tests, they get stuck at around ~95% for days.

Due to conflicting Data, not sure what actually is the issue and how to proceed.

Any help would be appreciated.

So it is the disk, thank you