Hey, so...these notifications are kinda wonky right now, huh? I'm sorry for the issues - I know it's made for a pretty inconsistent week this week. I personally haven't been getting mentions or reply notifications since Wednesday, so rest assured that we're aware of what's going on.
Again, all I can do is apologize for the problems. We're testing a large amount of fixes internally and hope to be rolling them out early next week. Sorry again.