Mobius RAID/4K sector drive compatibility
As of October 2017, hard drives with a 4K sector size (4096 bytes) are not compatible with Mobius 5-Bay and 2-Bay units. If 4K drives are installed in these units, the LEDs will turn purple and the drives will not mount.
The Mobius Thunderbolt 2 and Mobius Pro, however, are fully compatible with 4K drives.
For more info on the transition to 4K sector size hard drives, please see this white paper from Seagate.