using this adapter on my Ryzen 2200g-build (gigabyte ab350m-d3h) together with ubuntu 18.04 (latest mainline kernel –> 4.18-rc5 and latest mesa 18.2-devel and latest linux-firmware). With the adapter I can only use at least 30hz @ 3840×2160. 50Hz and 60hz does not work. If I connect the same TV (LG OLED) to the same pc (with same software) directly via HDMI 2.0 then I can select 50Hz and 60hz and it´s working. So the problem is related to the adapter.
Does anyone of use this adapter with linux and got 50Hz/60hz working?
Did you use a custom modeline for that?
Is maybe a newer firmware for the adapter available?