Users of Apple’s instant messenger service iMessage are experiencing some quirky behavior. Since December, users have taken to Apple’s Support forums to point out how certain phrases would appear cut off to the sender and receiver, when in reality, the final words of the messages were simply invisible.

The bug wasn’t a major concern until Twitter users began pointing out the problem last week, tempting their iPhone-using friends to try sending an iMessage with the phrase, “I could be the next Obama.”

When The Verge took notice of the increased Twitter activity on Friday, the iMessage bug was believed to be related to spelling certain words and phrases. For example, the two phrases “The best prize is a surprise” and “I could be the next Obama” both appeared truncated when sent via iMessage, especially when the message was sent with an extra space left at the end of the last word.

As Apple works on a fix for this issue, a user named “arian19” posted on MacRumors’ forums on Friday to explain what he believes to be the problem.

“Even if you change ‘I could be the next Odama ’… the phrase it still gets deleted,” the user said. “The problem is that the message app thinks the phrase will fit in a one line bubble, but it actually puts the last word on a hidden second line. It works with these two phrases because they are the exact width needed, and it is not based on character count, but character width. For example, ‘l’ is skinner than a ‘w.’

“Even the phrase ‘I old ube the next Obamac ’ will truncate the last word, because the string width is exactly the same, because all the same characters are being used.”

Apple users have noticed that the iMessage bug is unique to the iPhone -- iMessages on the iPad or Mac don’t appear shortened -- but copying and pasting the invisible messages from iMessage would reveal the original message in full.

We reached out to Apple to get an official statement on the issue, and when users can expect a bug fix. We’ll update this article as soon as we learn more.

Apple's iMessage debuted to users in 2011 as part of iOS 5, which also introduced popular iPhone and iPad features such as iCloud, Game Center and the Notification Center.

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