Yeah, the alot of settings are tied together on the MSI board. If the 4G is enabled, UEFI is automatically enabled as well and it won't let you independently switch the UEFI to Legacy Mode. If 4G is disabled, legacy mode is available, but then there is a 4 GPU limit.
glad to see I'm not the only one who has ran into this issue lol!
Jumping on the bandwagon here as well. I have one rig still running ethos because of this issue. Would love to see a solution that doesn't require me to get a different motherboard (ethos is working, so that won't happen - just prefer SMOS if I have a choice)