You can try the workarounds here. Just note that Twitch has been doing this to some user accounts on purpose in all browsers lately. So, it might not be on your end.
I need a way to disable this too. I typed '9mm by the inch' into the search bar in order to find the data set at http://www.ballisticsbytheinch.com/9luger.html, but hitting enter just copied 0.35 into my clipboard very unhelpfully.
Seems like by default registered Opera application is a wrong one, i.e. Logitech is not recognizing it. I deleted it from Logitech Options and added once again (selecting Opera.exe from the installation folder). Registered custom keys on it and all works fine!
Turn off the Hardware Media Key Handling flag, close Opera, and then restart the Windows Explorer process. Then you should be good to go from there on. See this post for more info.