I recommend removing all the drives and attempting a pin-hole reset (with no drives inserted) and see if that helps. Make certain the Drobo is OFF before removing or inserting your drives, unless you want the drives erased.
All the comments I see elsewhere indicates that a pin reset will erase all data on drives.
Am I preventing this from happening by taking drives out first?
Will it wipe them when I put them back in?
As long as the Drobo is OFF before removing or inserting the drives, and as long as they’re not installed when you use the pin hole reset, your data should be safe. Having another backup of important files is always the best policy though.