This morning the Internet was abuzz with reports that Instagram was tracking and deleting photos uploaded to its servers from third-party Windows Phone app Instance (curiously, similar third-party apps including Instagraph and Hipstamatic Oggl never stopped working). The reason, it turns out, is that Instagram wasn't blocking Instance uploads on purpose at all. A company representative reached out to us to explain that the deleted photos were due to a routine security update:
We recently made an update to the systems that we use to fight spam to help prevent future attacks and increase security. As part of this, applications accessing Instagram against the terms of our API may also be affected. This update does not specifically target any particular app or platform.
Unlike a number of similar Windows Phone 8 apps, Instance, which was developed by "Microsoft enthusiast" Daniel Gary, works by subverting Instagram's API to bypass its security system and upload photos to its servers. That's why the update marked Instance uploads as spam and deleted them.
Whether or not Instagram knew its update would block Instance, the company clearly took note of all the attention the news received online. It looks like a second update was pushed out about an hour ago, letting uploads from the Windows Phone app go through but blocking them from showing up in other users' feeds.