Activity Streams: Custom Marketplace Stream Not Working

[Joy Rex]

I really like the idea of the Activity Streams, so I thought I'd make a custom Activity Stream here to test it out - I always want to know what's new with Marketplace items, so I created a stream based around that:

Showing files in Utilities and Stats, Developer Resources, Member Extensions, Staff Extensions, Fields, Social Experience, Multimedia, Bridges and Integration, Commerce and Blocks and Widgets posted since my last visit.

Thing is, I've had it running for a week+ now, and every time I visit, it says there is nothing new - I checked, and there have been new items added to the Marketplace within the last week, so obviously I have something set incorrectly, or it's not working as expected.

Here's the other options I have set for the stream:

 

[Joy Rex]

Now odd items like "stream_title_346" and "stream_title_350" are appearing in the Activity dropdown - what's going on?