First, this is absolutely fantastic. I’ve encountered a bug, and I think I know what’s happening.
Here is a cluster in my News folder. Semafor is the “main” story and the Engadget one is in my Tech folder.
If I click the Engadget story to view their coverage, the browser is redirected to the Engadget feed in the Tech folder (I can see the URL and the selection UI in the sidebar), but the story does not open.
In my limited testing, if the clustered story is in the same folder, it opens correctly.