The 4mh bug occurs with windows 10
The 4mh bug occurs with smOS
So xfx and sapphire cards have this more then MSI rx cards.
Try hooking up 1 card to a monitor if it is still there
They hooking up card 2 to a monitor if it is still there
Try hooking up card 3 to a monitor if it is still there
Try hooking up card 4 to a monitor
If it is still there after you tried all six cards try bios switch on first gpu if it has one.
Lastly are your cards flashed with a custom bios. That may be your issue
Maybe it happens for some people on other OS. I can only tell you my personal experience.
No it doesn't happen with ethOS or Windows10. I'm sitting here running all 6 cards full speed dual mining on Windows 10 right now. I turn it off and run off the USB stick that has smOS and it doesn't work with smOS. One card runs super slow.
Claymore miner on all 3 OSs.