Stream Missing Tweets but get No rate limit messages


We’re running the Public Stream filtered with by roughly 4700 users. We seem to miss a large number of tweets from these users. If we query the search api for the followed users, we find the missing tweets. We don’t get any rate limiting status messages (we tested the rate limit mechanism was working by adding the tracking text ‘the’ and immediately saw the rate limit message come from the stream).

Are their any other reasons we could be missing these tweets? The users we’re following aren’t private or protected.