4th drive missing after relocating

I just moved my drobo from my desk to the closet. I booted it up like normal and my 4th drive is missing and the drobo is managing my data now (for the coming 40hours…). I’ve got 2x1.5tb and 2x1tb of drives in it, with about 1.7tb used. I guess I’ll just let him do his thing, but this isn’t typical behavior, is it?

This exact same thing happend to me. I dont think the drobo drive bays are very secure in there mounting it could do with a side spring to keep the drives pushed into the right postion. Like the back spring but at the left hand side (facing the drobo).