Same problem here. 007s risers and MSI Z270-A PRO.

Connecting GPUs to the PCIx16 and PCIx16 working as x4 is working fine, but when I use a riser no GPU is detected. I've tried with 5 different risers and 3 different GPus and none of them are working... u_U

The PSU is working fine.

Updated bios without results.