Edit: The issue hasn't occured anymore within the last two or so weeks, everything is now working fine again. Thanks to whoever fixed it!
I use RSS feeds to receive notifications about new questions via several tag filters1 according to custom defined tag criteria (I subscribed to the RSS feed for each filter, as found in the bottom right corner on the corresponding tag filter site in the browser).
In the recent days I have noticed that every few minutes, in each feed a large bunch of old messages is randomly marked as new. They do not appear as duplicate new entries, but are marked as unread/new with the old timestamp, although there was no new activity in these threads.
I took some sample cheks with the affected threads and there was nothing that could have triggered sending out a new RSS notification - no new answers, no new comment, not even an edit; the last activity that I could see sometimes took place several days ago.
Anyway, the feeds should inform me only about new and not recently active questions (this is how it used to work before and I made sure to include
?sort=newest at the end of the RSS URL).
The issue does not seem to be caused by my RSS feed reader (I use Bamboo Feed Reader for Firefox) - other readers receive old RSS messages from SE filters as new ones as well.
Additionally, my feed reader doesn't show old messages as unread in feeds other than Stack Exchange filters.
Also, when I view the filtered questions in my browser, everything seems alright, there are no old threads on top (neither in "activity" view, nor in "new").
This leads my to the assumption that there must be something wrong with the RSS feeds, randomly sending out old questions with no recent acitity as new feed messages.
The alleged bug is very annoying, because every few minutes I receive RSS notifications most of which turn out to be no new activity at all.
Could this please be fixed? Or am I doing something wrong? As far as I remember, everything has been working fine until about a week ago.
1These are the affected feeds: