I read your post when you initially posted, but I missed this part!
Which power adapter cable?
If you’re talking about the one included with the FWL16 power adapter… I think I vaguely recall that might be your problem. I could be remembering wrong but I think it’s not alt-mode capable. Fully featured thunderbolt cables that do everything are expensive and tend to be thicker, stiffer than non all-in-one cables. Since the cable was intended for charging FW didn’t see a reason to charge people more for something they may not need + have it be thicker and stiffer. Always have to check what a USB-C cable does. If it’s not labeled with a speed, can’t assume it does anything more than what you already know it does.
~edit~
Memory is good for something afterall 