Problems with multimedia in QtWebEngine

Hi all,

some time ago (week?) multimedia stopped playing for me in QtWebEngine-based software in Tumbleweed (namely, I am using Qutebrowser and MellowPlayer actively). All other software (including sample video player from qtmultimedia repo) seems to work, so I assume problem is indeed in QtWebEngine. I am not experienced in debugging this library, any good advices where to start?