Firstly; thank you for new version 0.12.7 beta.
tried and worked well! Regards.
But my hashrate for Sapphire Nitro RX570 4 Gb Hynix - x22i - 3,1 Mhs
I am waiting information abouth best oc & other settings.
Did you try optimal parameters I have shared in OP? Also this is not bad result, if you are running your gpu with some undervolt/underclock. My tests are done for stock clocks and modified timings for memory.