Z370 Taichi showing error 15 on every cold boot

System:

Z370 Taichi on latest BIOS (4.20)
8700K
G.SKILL 16 GB (8x2) 4266MHz F4-4266C19D-16GTZR

Kind of an annoying issue, but pretty much every time I perform a cold boot on my system I get an error 15 code and the system hangs. I then hold the power button for a couple seconds to power it off and then power it on again and then it boots fine. Sometimes this takes more than one try.

I know error 15 is memory related, but this kit F4-4266C19D-16GTZR is listed on the memory QVL list for this motherboard. I already tried lowering the frequency, but it doesn't solve the issue. As it stands I'm using my system just fine with the memory at its rated speed 4266MHz, but I always have that routine to get it running.

Is there something I can do about it? Any help is appreciated.