Not recommended at all to use RAID controllers with Unraid, you should use a standard HBA instead, still might have issues now if the RIAD controller wrote anything to the MBR of the disks, and it likely did, it could work if you rebuild all the disks one by one, like users need to do when going from RAID to HBA, but like mentioned it's not recommended.
There should be no issues outside or inside an array as long as you don't use a RAID controller, with one it might work, it might not.