Have you tried resetting the SMC and NVRAM on your Mac to see if this solves the issue?
The fact that it doesn’t happen on USB and you only see it on Thunderbolt suggest a driver related issue on the OS. You can reset your SMC which essentially rewrites your hardware profile for the system and can solve issues such as these and non recognized drives.
Here is Apple’s direct article on how to reset the SMC and NVRAM. Resetting the SMC
Hello friends
I’m new to this web
I have a problem, I use the (G-Technology G-RAID 12TB 2-Bay Thunderbolt 2 RAID Array) stopped working via Thunderbolt, only USB works, maybe someone went through that or some solution?
20 min is just an estimate. It seems to vary a little bit but somewhere around there.
And yes, for mine, I always have to wait a duration from a cold start in order to use Thunderbolt. After the ~20min, I can unplug and replug the Thunderbolt and it will mount immediately. USB works perfect.
I feel this is a fault in the device but as you can see from the above, WD wasn’t able to recreate it in their labs. I’ll probably return mine for warranty repair as soon as I get some time off editing work.
Let us know if this your condition as well. Curious.
Just an update on this – I sent the drive back under warranty and I think it was replaced with a refurbished version. It now recognizes pretty quickly – not as fast a USB but reliably.