Instagram launched as a beta on Windows Phone quite some time ago, and while at that time, the company announced that "our team will continue developing the Windows Phone app to keep releasing features and bringing you the best Instagram possible," it is important to note that the app hasn't been updated in the past 17 months and is quite sub-par as compared to its counterparts on Android and iOS. Now, it appears that instead of the app being updated on Windows Phone, it has broken down.
WMPoweruser notes that the service doesn't refresh its feed on the Windows Phone app, but is working fine on Android, iOS and the web. Looking at the situation, its quite possible that this is likely due to the recent changes in Instagram's API. As the service also introduced support for non-square images and video, this could be causing a bug in the app as well.
With that being said, the root of the problem and whether the company is working on a fix currently unknown, but we've contacted Instagram regarding the problem and will let our readers know when we hear back. In the meantime, if you want to try your luck, you can download Instagram BETA for Windows Phone from here.