The problem seemed to go away when I changed “Disable activity stream commenting on blog and forum posts?” to Yes (under BuddyPress General Settings).
Just an FYI, the replies that disappeared were to forum posts, but the notifier email said they were replies to an “update.”
I’d like to also be able to disable activity stream commenting for Updates too, but now I am not sure if that is necessary.
Of course it would be nice to allow activity stream commenting on forum posts…. but I just can’t take the chance that any replies to forums will be lost. The forum is a central feature and selling point for my site.
During the period that this problem started, I had:
+Tried to “connect to WordPress.com” using JetPack button, only got my homepage, looked at the features of JetPack and decided to deactivate and delete it.
+Added, then deleted, the Twitter Connect plugin.
So I guess it’s possible the problem happened in the install and uninstall of those plugins?
Did anyone else here do something similar with their plugins prior to having this problem?