Hey guys, thought I'd address the issues raised here myself
With regards to the OP's problem, there are a few reasons the tile could fail to update, the only way I can diagnose this is on a case by case basis I'm afraid. Luckily I added the tile diagnosis screen which you can find in your live tile settings within the app. If you think the tile is failing to update that's the first place you can go. Find out what the "last exited reason" was and then let me know. If it's network update the likelihood is the task ran while the screen was locked and you had no network signal (WiFi takes too long to fire up and the OS kills the task, hence you get a network error).
If the task isn't showing as scheduled then something else is wrong altogether, and would need me to investigate with you a bit more.
As to the "20" issue, it happens when an article is posted on WPCentral and then taken down (most commonly the live podcast article). The app registers that article as the last read news item, then the next time it grabs the feed to count how many articles are new it can't find that article. Therefore it counts all 20 items in the feed and displays the count of 20. This only happens occasionally and is not something I plan on fixing, as I'd have to make the background task MUCH more inefficient to solve it.
If you have any other questions let me know, or of course you can use the feedback option in the App's about screen, I endeavour to reply to all feedback I receive
Oh, and keep your eyes peeled for the v2.0 beta...