Hi, I'm sorry for reviving this topic again, but I have the exact same issue. Since Jim_Brown hasn't replied to your solution, I'm not sure if it helped.
I configured my WD My Cloud EX4100 with two 8 TB HDD's to RAID 1, bays 3 and 4 are not occupied. Nor have I tried to reset the NAS.
- will placing the disks from bays 1 and 2 to bays 3 and 4 or resetting the NAS affect the data?