SMART errors, and the drives were refurb's - have a few others that have worked for years but apparently these did not.
I moved the drives around in the cage to 3 different slots, no luck.
After the error unRaid would kick the drive back to the unassigned devices location and show error/unmountable.
So if you ever have an urge to buy from Water Panther, be cautious.
I'm sure they are just a labeler, but who knows where they get their drives.
Will stick with HGST & Seagate.