Occasionally I refresh and clear read posts only to see a couple posts I just looked at a short while before not marked as read. On opening them again the event log indeed shows a duplicate action for marking the posts read.

Anecdotally this seems to happen for a handfull of posts at once, and I notice it every few days, usually with posts I looked at towards the end of my browsing session. Sometimes a few minutes pass before reloading and finding the post, so I doubt it is some race condition.

I have observed this for a few months now.

Could this be an app issue or is it an issue with my instance?

Has anyone else experienced this?