what make/model hdd's?
try enabling hot swap for each of the ports in bios,that sometimes works
have you got anything in the M.2 slot or the lowest PCIex16 slot
Nojust for clarity are you drive all in the Intel ports or are some in the Asmedia ones? also do they show up in the Asmedia one and if not is the Asmedia controller enables in the BIOS.
I see all eight in the Bios
sorry for the rambling questions Keep on asking, I have never had these problems before
edit p.s. are the 3 that don't show up on the same SATA power cable?