My iMac Pro didn't like the long cable I used to power the TimeMachine backup drive. iMP crashed several times due to kernel panic. Removed this cable and the problem was solved. There's a reason the Apple Store does NOT offer this length for Thunderbolt3. Got a very constructive answer from Neckteck about the difference between active and passive cable. Obviously, the redundant disk in question can only work with passive cables. Neckteck found the right cable for my system. I understand Thunderbolt 3 technology is more complex as the active and passive definition is determined by the device you want to connect. I've changed my original rating to a full 5 stars and applaud the customer centric approach.