Not 100% related, but it's always advised to flash your controllers to be in IT mode, not IR mode. Lessens your problems, and is the recommended for pretty much every software RAID out there, including Unraid
Because of the IR mode flashing, SMART is currently showing up for the affected drives, but since most actual hardware failures are exceedingly rare, it is likely because of poor cabling connections to the drives. Reseat at a start
Other than that, since writes to the parity drives failed, the drives were disabled. You need to (after reseating)
Unassign the parity drives
Start Array
Stop Array
Re-assign the parity drives
Start Array
A rebuild of the drives will then commence.