Help with Facebook notifications

I belong to a number of groups and have always been able to follow individual posts in those groups by turning on notifications for that post (using the 3 dots in upper right of the specific post). A few months ago, I stopped receiving those notifications on both mobile and desktop. I have tried everything - restarting, reinstalling, checking that notifications are turn on in all settings and nothing works. When I turn on notifications for a post, I get the pop up confirming that notifications are turned on but do not receive any when new people post comments. I only receive notifications if someone comments on my own posts but not other posts in my groups. Anyone have any ideas as to what I can try? I may have to resort to commenting 'following' on any post I want to follow which is annoying. First time here and I haven't figured out how I can post this in the specific FB help forum so hoping for the best.