My Mobius spontaneously disconnected after long period of use.
Mac:
If all of the LEDs are blue, and there is no indication of a drive failure in RAID Manager, it indicates that the issue is not due to a faulty hard drive. If a LED is red, that indicates a drive failure.
If the Mobius is present in Disk Utility, but not mounted, I suggest running a Verify/Repair in the First Aid section of Disk Utility. It may be able to solve the problem if it is related to the partition table.
If you still have trouble, we suggest Disk Warrior, which will often solve issues that Disk Utility is not able to resolve. http://www.alsoft.com/DiskWarrior/