I´ve got the same problem. Had just opened a new thread as I didn´t see your post, sorry.
Seems to be caused by the new version 63.0.3368.71, if you ask me.
To try out, if it is caused by adware or a virus, I just installed a clean system image from 8th of august 2019 with Opera 62.0: the short cut worked. About 20 minutes later Opera updated itsself to Vs. 63.0.3368.71: the short cut didn`t work any more. So I suppose its not caused by adware or a virus. And neither by win7.
I also tried - like you did - the reset options of opera: also without success. It looks like we have to use our comftable mice instead of the short cut, we are used to, if we want to erase the browser data.
P.S.: Sorry for opening a new thread an hour ago. I didn´t see this post. Nomen est omen ....