Tweets from users you follow may be missing from your timeline 2 years ago

We are currently working on a critical bug whereby some tweets from users you follow may not appear in your timeline. This bug particularly affects the delivery of tweets from users you follow that themselves have a large number of followers.

We plan on deploying the first part of the fix for this bug tomorrow morning and will update status thereafter.

Update: We deployed a fix for one of the underlying problems and are assessing its success.