I’ve been dealing with this for 7 months now. On a 2019 iMac.
The drive stops responding and the finder goes into spinning beach ball mode. I have to shut down the machine and restart. EVERY. TIME. It’s a nightmare.
Support was very helpful at first but now they’ve kinda just dropped off. But replacing the unit has not worked. Replacing the cable makes no difference either. I’m not sure what the problem is. I think there might be some kind of issue with their kernel extension and the System Integrity Protection on the Mac. I keep meaning to try turning SIP off but have not done so. For now I just keep the drive disconnected until I need to use it.
I’m really hoping Big Sur solves the problem but I’m not convinced. Still not jumping in that pool for a few more weeks.
Strangely enough I have another Shuttle-XL hooked up to a 2013 MacPro running Sierra via TB3 to TB2 adapter and it’s rock solid.