I don’t know what I did! All I did was install a drive, then go into the Storage tab and add the drive to the current pool, restart the server and BAM - this happened!
All of the drives installed to the PC are listed. I just noticed I mistyped the quantity of them though.
x1 M2 240gb drive
x1 SSD PNY 240gb drive (boot pool I believe)
x1 4tb WD drive
x2 3tb WD Drive