Just signed up to thank you for this post. I figured out that I had to roll back my driver to the Crimson Relive 17.8.2
http://support.amd.com/en-us/kb-articles/Pages/Radeon-Software-Crimson-ReLive-Edition-17.8.2-Release-Notes.aspx (the one you linked to is bugged for me and others according to the patch notes) to keep the Afterburner compatibility.
Although I will say that I had this issue with the RX 580s, so I don't think it has to do with the pixel patcher since, as you said, you don't need to use it to mod your bios. Seems like it's an issue with Afterburner but obviously I can't know for sure.