Unable to open iMessage app extension

I was able to use the latest version of the XCode project manipulator API to add an iMessage app extension to the XCode project built by Unity in a post build hook. The project can then be built and installed on device, the iMessage app being installed alongside the containing Unity app.

However, while the Unity app appears to work fine, the iMessage app extension fails to load, stuck on a screen with the app icon, failing to proceed, and appearing to be completely frozen. When XCode...

Unable to open iMessage app extension