I don't know if this is a bug or anything or if it's intentional but Opera GX and Google Chrome don't have the same features. If this has been said on any other threads I'm sorry.
Well, another user named @sebast83 had also reported two problems. Read them here and please tell that do you have the same problem so the developer get a reason to improve the game on Opera browser.
Boss at Pro Manager Guiders
Be the one who thinks for all, just not for himself! #SaveOSM