Based on the link you provided, it seems to be a recurring issue. So I suppose we need to restart Ghost instance once a week to get the analytics correct? This is problematic as I have to share the analytics with newsletter sponsors.
Perhaps it’s not completely a self-hosting issue? I recently noticed that according to my member activity on a colleagues’ Ghost(Pro) site (that I’m a paid member of) that while I get recorded as having received emails, I don’t get recorded as having opened them. Taking a closer look at it just now I can see that while I was recorded as having opened up every email up until 02 Nov 2024, starting on 21 Dec 2024 I’m listed as having only received the emails.
I suppose this is something I should be taking up with Support rather than here on the forum…
If you’re getting SOME open rate reports, just not for that user, I don’t think it’s a Mailgun analytics problem. (If you’re getting no open rate across all users, that’s a Mailgun analytics problem, and a restart and other troubleshooting is indeed in order.)
However, individual users may read your email in mail clients that block open tracking, either as a deliberate setting, or as part of blocking image loading. Open tracking numbers run low as a result, and seeing people who never open still click your links (in ways that look real - see below) is just a thing that happens as a result.
Meanwhile, click tracking is often inflated, because some security scans “click” links, so it’s possible to see all the links clicked on an email the user never opened. It’s all maddening, really. The link clicks that happen in the seconds after sending are probably not real.