I can confirm that ASRock Fatal1ty AB350 Gaming-ITX/ac is working on my side. With R5 2400G, it provides 4K@60fps output in both WIndows 10 and Fedora 27, though Fedora incorrectly recognizes the GPU as "Vega 8 Mobile".
I would check functionalities of RGB 4:4:4, HDR and Freesync in Windows 10...