Why aren't some of my devices installing an app store app?

Problem

If app store or VPP apps are not installing on iOS devices, you may be running into a nuance of iOS.

When an app is pushed to a device, the device may prompt the user for:

1. An Apple ID
2. Permission to install the app
3. Permission to update the currently open app

If any of these prompts are cancelled or denied, the app will not install. Confusingly, if you try to push the same app to the same device, the device will not show the prompts again and it will not install the app. Apple has designed iOS to avoid re-prompting the user with the same question if they avoided it previously.

A common scenario is:

1. An app is pushed to a device
2. The device prompts for an Apple ID because no VPP licenses are available for the device. The user cancels the install.
3. The SimpleMDM purchases additional VPP licenses and re-pushes the app.
4. The device does not prompt for or allow an install

Solution

To resolve this issue, the device must be turned off and turned back on. Once the device has restarted, the SimpleMDM administrator can re-push the app for a successful install.