Just downloaded Opera GX, I went to Youtube an ad started playing so naturally I installed uOrigin Block immediately and deleted the built in addon. Now half the videos I open have a Youtube error code and I have to refresh the tab for them to start playing.
This never happens with uOrigin Block in Firefox or Chrome. I assume the issue stems from the way Chrome addons are being installed in Opera.
Currently running Windows 10 Pro 1809, Build 17763.529
Not sure where to grab the Opera GX version, but I assume it's the first public build.