Hi,
I have the exact same setup as you.
Z370-HD3 firmware F8a, with 32gb Ram, Sapphire 580 Nitro+. Could you please share your Bios settings and latest EFI and config.plist that works with Mojave Beta 4 and 10.13.6 if you have those.
I have downloaded the Olarila Mojave Beta 4 image but it seems to hang after AppleHDAEngineOutput with message Endpoint has been activated through legacy API's?? Would I be better staying on High Sierra?
Many thanks for any help