RAID recovery won't proceed — "Next" button stays disabled when selecting the replacement disk

Operating System ZimaOS
1

What I’m trying to do:
Recover/rebuild the RAID using the WD sdc drive.

The problem:

  • I go to Storage → RAID Recovery → Start.

  • The “Recover Data” dialog opens. The only selectable drive is sdc; the 5 Seagate members are greyed out as “Used”.

  • I tick sdc, and the bar shows “Recover to 5 TB” with protection/redundancy. But the Next button stays disabled — I cannot proceed, no matter what.

  • I’ve tried [rebooting / formatting sdc — write what you’ve tried] and it still won’t let me continue.

Questions:

  1. Is the Next button disabled because sdc still has old RAID metadata? If so, what’s the safe way to fully wipe only sdc without touching the 5 Seagate members that hold my data?

  2. Is this a known bug in the RAID recovery UI? Any safe workaround?

  3. If it has to be done via SSH/mdadm, could someone share the exact steps? The data on the Seagate drives is important and I don’t want to lose it.