MP 6,1 2013 Mac Pro external drive unmount problem

[SignalHill]

I have a 2013 Mac Pro. This machine is used exclusively in my recording studio. OS 10.14.6. Sometimes when I try to shut the computer down it sticks on the black screen with spinning gray wheel and will never shutdown, even if left over night. I have to hold the power button to force a shutdown. The issue seems to be that the external hard drives do not unmount.

I can tell when this is going to happen because when I click "ShutDown" the two front panel lights on my thunderbolt G Drives do not do the typical FLASH. They simply stay static. If I cancel the shutdown and go to disk utility and try to unmount the drives they won't unmount. Usually when this is occurring Disk Utility gets stuck on the Loading Volumes step or simply won't open at all. Dragging to trash doesn't do anything either. Today I have a third drive (Crucial SSD USB) connected and it won't unmount either.

Where do I begin?

 

[andrewv69]

try relaunching finder. your exact scenario hasn't happened to me but i usually have external usb drives plugged in, and sometimes they won't eject when i want to remove them. relaunching finder usually fixes whatever issue then allows it to eject. might be something with the drives not ejecting that's hanging up the shutdown process. though with my drives it has never stopped a shutdown so idk, try it out.

 

[SignalHill]

Ahh yes I actually did they that. Finder restarted but the problem persisted. Also attempting to logout has the same effect as shutting down - just gets stuck.