@leocg I tested it on some sites like Youtube, Twitch, Dailymotion ... they are working perfectly. But I can't pause or play Udemy videos. I believe the Udemy was open in the browser when I logoff.
I also tried to follow the instructions in this post "https://forums.opera.com/topic/39910/instructions-on-posting-about-problems-in-opera-gx" and tried to follow the instructions in several other posts here on forum, but I was not successful. I also uninstalled and deleted all Opera GX files that were saved on my computer, but the error still persists.