X9DRI-F here. Yea, have to report the Asus Hyper M.2 didn't work for me either. Due to physical fit of the card and memory slot I can only try in the x16 of slot 4 and slot 2. Neither worked and only reported 1 of the 2 NVMe drives I had in there (I tried NVMe position 1&2 and 1&4).
I had actually bought an X9DRI-LN4F before - but it wouldn't fit in my 4U case
so I moved to get the X9DRI-F. Ah well. I'll just get two simple x4 brackets and do it that way. I don't have the CPUs in that one else I'd test to provide another data point. Fortunately have enough slots to get by with what the server needs to do.
Given the compatibility for the AOC-SLG3-2M2 it seems bifurcation is a bit 'jank' at this age of board. Ah well. Maybe when I next 'refresh'.
Having posted this it just occurred to me that I am testing with cheapo E5-2620 Xeons. I do have some E5-2673 v2s on order. I'll re-test with those and report. Since PCIe is very dependent on the CPUs, I wonder if that might make a difference?