RAID Degraded- Please Help

I recently set-up a RAID (Mirrored) set on a brand-new G|Dock ev w/thunderbolt. Each drive is 1TB, the drive labeled “2017 Clients” is being mirrored by the other.

I am constantly switching between working from my iMac & MacBook Pro. I just returned home from traveling and was working off “2017 Clients” drive, I left the backup drive in the port at home. I just inserted the dive I’ve been working off while away and now I’m getting a message saying “RAID Degraded.”

I’ve attached a few photos for reference of the messages. Not sure if I set something up wrong or what. The programs I primarily use are Lightoom, Photoshop, and Premiere.

Please advise, thank you!!