Hey! I'm having the same/similar issue. Bought a splitter from amazon (this one) I had the same issue with my rig not turning on at first but then was able to get the rig started. After about 10 mins of mining, I had a "No power consumption" error for the GPU connected to the second PSU while the gpu's for from the first PSU were fine and still mining. Just wondering if you were able to get them to run fine?

Setup:

1ST PSU (750w) Connected to main spliter head> mobo (24pin & CPU), 2 gpus (connected directly to mobo for now).

2nd PSU (850w) connected to secondary splitter head > 1 gpu (riser and GPU) (planning to add 2 more but wanted to test one gpu first in case anything went wrong)