Update below that shows both first and third party apps are affected.
If you use Twitter’s app for iPhone, you may be missing some of the times your username is being referenced, and sometimes they are being ‘replaced’ by older retweeted mentions. This bug was discovered by the folks at Favstar, who have detailed the issue in a blog post.
They explain the problem like this:
It turns out @Twitter for iPhone will sometimes not show a mention on their Connect -> Mentions tab. This seems to happen when an older mention has been retweeted by another user, which takes the place of the mention that should be there.
I went about attempting to reproduce the issue on my own devices and found missing @mentions right away. They appear in Tweetbot for iPhone (as well as the web version of Twitter), but not in the iPhone app.
The example above isn’t an isolated incident, either. Scrolling through the list of mentions resulted in a half-dozen examples within a few pages. The mentions are simply not there. I had been noticing this for a while, but wrote it off as a glitch, but it seems to be widespread, as others are saying they’ve noticed it as well.
Here is one of Favstar’s examples, showing a missing mention from ‘paulshipper’ being replaced by a retweet from ‘Shockingly Apt':
Obviously, for a communication platform, missing mentions of your name is a big deal. Some days I live and die by my mentions, getting tips, corrections or perspective from those who choose to contact me on Twitter. I mean, if Twitter eventually wants us to use their apps as the only way we view Twitter, the least they could do is show us all of our mentions.
So, if you use Twitter for iPhone and depend on your mentions, you might want to check through your list of mentions to see if you’re getting them all. We’ve reached out to Twitter to see if this is an issue they’re aware of.
Update: Applespotlight shared an interesting comparison with us that demonstrates the issue happening in both the Twitter app for iPhone and the third-party Tweetbot.
The existence in both first and third-party apps appears to indicate that this is an issue that may stem from Twitter’s API itself not delivering every mention to you. Essentially, you can never be quite sure that you’re seeing all of your mentions if you’re using an app instead of the web, ever. The universe is caving in.