WARNING – The latest security updates for both 10.14 & 10.15 may disable the inner-most usb-c/thunderbolt port on iMac Pros. I have two Macs with the same issue. One on each OS. The 2nd mac was working fine until the update was installed, then the port was disabled; pointing directly to the security updates as the culprit. A T5 SSD connected to this specific port shows no power light. The same result appears on both affected Macs.
This is the port next to the ethernet port on the iMac Pro. Radar has been filed : FB7639274
This is the port next to the ethernet port on the iMac Pro. Radar has been filed : FB7639274