I have both the Opera and Opera GX browsers.
Opera Version: 69.0.3686.77
Opera GX Version: LVL2 (core: 68.0.3618.197)
In the Opera browser, when I go to the Extensions Manager, and go to a certain extension, and try to uncheck the "Hide from Toolbar" option, I find that it no longer there, and missing.
I opened both browsers, and took screen shots of my Adblock Plus extension, to show you what I am talking about.
Opera - Adblock Plus Extention - Details Page:
Opera GX - Adblock Plus Extention - Details Page:
It appears to be a problem with the #extensions-toolbar-menu flag, which disables the icon that lists all of your extensions. I have this flag disabled on both of my Opera, and Opera GX, browsers, and it has worked beautifully, and had never been a problem, until Opera updated itself recently. I disabled that flag, then I would just go to each individual extension, and uncheck the "Hide from Toolbar" option if I wanted them to show on the Extensions Toolbar Menu. I can't do that anymore, because "Hide from Toolbar" option, has been removed from all of the extensions.
I also expect that this problem will replicate itself, when Opera GX next updates.
When I try to Enable the #extensions-toolbar-menu flag, it no longer works either. It doesn't put the icon, that lists the extensions, back on the Extensions Toolbar Menu. So, I can't access it that way either.
In interesting side note, in Google Chrome, The "Hide from Toolbar" option is missing from all of my extensions, just like in Opera, but the #extensions-toolbar-menu flag, DOES work, and DOES put an icon that lists all of my extensions, in the Extensions Toolbar Menu, which DOES allow you to pin, and unpin extensions, to and from the Extensions Toolbar Menu, which in turn makes them accessible. I wish this still worked in Opera.
So, it appears that the new pin / unpin functionality, that goes along with the new Extensions Toolbar Menu Icon, has somehow broken the #extensions-toolbar-menu flag, in Opera.
The "Hide from Toolbar" option, for each individual extension, needs to be restored, so that people, that disable the #extensions-toolbar-menu flag, don't lose the ability, to add, and remove icons, to, and from, the Extensions Toolbar Menu.
I can't add any extensions to the toolbar, so that I can use the extensions. With this option missing, there is no way to access the extensions, and use them. This problem is the same for all of my extensions, not just Adblock Plus.