We recently upgraded a small community from IPS 3.4.6 to 4.4.10, and we've been mostly happy with the changes, but there seems to be a major problem with the notifications system. It seemed to work correctly for the first ~3 days, but since then (about a week ago) I haven't received a single notification icon or email for my followed topics. I don't know if it's affecting the entire community or not - I can see that there are emails repeatedly being sent from the server to some users, so I assume that some people are getting their normal subscription emails and I haven't received any support messages about the problem yet. However, I've spoken directly with a couple of members who have confirmed they're not receiving notifications either, so I know it's not just my settings, and I've tried every setting (in both the admin panel and my own notification setting) that could affect this.
Has anyone else experienced this, and if so, how did you solve it? I know the first option should be, "open a support ticket", but the last time I tried that I was rather tersely advised to "upgrade to 4.5.3". We're not ready for that just yet, and I'd really like to know why this issue is happening first.