Drobo not mounting in Windows 10, says partition is unallocated

I have an older Drobo disk pack that is now being used via a USB port to a Windows 10 machine. It’s been working with the Drobo formatted with NTFS for a while now, even sharing the drive volume over a network, no problems.

After a roboot of the system, the drive no longer mounts. Drobo Dashboard show it is there and that is has some used space, some free space and everything is fine. But Windows shows the drive is unallocated any wants me to initialize it.

Any ideas how I get the the drive and data back online? Thanks.

If you have access to your data you will need to backup all of the data on Drobo. Once you have completed this process, you will need to start over with Drobo: