Was having a similiar issue, and this fixed it. Seems the easy file feature has a conflict with windows explorer. Anytime I tried to upload a file to any website, facebook, email, dropbox, youtube, etc. When I got to the step where windows explorer would normally open and allow me to select a file Opera and Opera GX both would freeze, unable to switch tabs or close the Opera windows/tabs. Also would occur when trying to save/download any files that required the windows explorer to open to select a file location.

Turning off easy files fixed this issue for me.