<applicationInitialization> documentation doesn't cover IIS mechanisms that can block initialization despite of proper configuration.

[ActomicIceBreaker]

Application initialization feature documentation doesn't explicitly tell, that there are several features than can block it despite proper (according to documentation) configuration. Int need to be specified that appInit requires HTTP (so no SSL) access to the application so:

1. SSL Settings -> Require SSL (which will bounce any http requests with 403)
2. Inbound rewrite rule which redirects all requests to https (with status code 303) will effectively prevent the initialization from happening.