I have this exact issue. I right clicked an extension to go to options and accidentally hit unpin, which is poorly placed... I can't find where to re-show it. It isn't anywhere in the extension options, in the extension details, or even on the main extensions page.
This is a vital extension that I am required to have access to for the browser to work properly. If I visit a new site, I must be able to configure what is allowed and what I block and right now... it will block everything on new sites I visit making the browser un-usable.
There must be a solution to this.
Go to your settings, select recovery you dont need to erase your bookmarks and passwords, select the first option. and boom! Solved!
I was very upset with this for a few weeks and until today i had time to find out how to fix it.
Hope it works for you, also im using latest version 70.
In Opera Touch they have something like this called My Flow. If you look you'll see there is already a thread requesting to bring My Flow to Opera for Android - look over the description, and if it does what you want then support that thread instead.