If I select Activity Stream → Content I Posted In then I only see threads that I have posted in within the last week or around that time.

 

The Time Period is set to 365 days and making changes to it, does not change the results.

 

Also, if I thread I have posted in (e.g. 2 weeks ago) receive new posts, it does *not* show up in my activity stream.

 

This problem has existed for 6+ months, presumably it started after the forum had that major upgrade (~1 year ago?), it worked in the past (many many months ago).

 

11 hours ago, lkn said:

If I select Activity Stream → Content I Posted In then I only see threads that I have posted in within the last week or around that time.

I noticed the same.

Somewhat annoying.

A workaround that seems to work:

open your profile page and click on "Posts" or "Topics".