If you click extensions button (wire cube) on toolbar, do you see your extension? If yes, then you can pin it there.
Sorry for the delay. Many thanks! That worked. I had no idea that option was there. I never did it before, and I've always had this extension on the toolbar. The Extensions page does not show the pinning option, and that was what appeared after I (re)installed the extension. So it feels like something changed without notice. IAC, it's working now, and all is well.