Itunes connect mobile not updating
It's possible that you're trying to update an app that is out of date and no longer supported by i OS.
Before you turn this on beware that it could mean that your i Phone uses a lot of data downloading updates.
Work networks, for instance, may be set up to block certain sites and services to preserve bandwidth.
Try using an alternative Wi-Fi network and see if that fixes the problem. If you are accessing the App Store over your 3G or 4G connection, that may be the root of your issue.
While using your mobile network connection shouldn't stop you from accessing the App Store entirely, if your i Phone is set to only download apps over Wi-Fi you won't be able to download apps over a 3G/4G connection.
Try connecting to a reliable Wi-Fi network and see if this allows downloads to go ahead.