Steve_PrenticeI'm not sure if this is down to how I've split out our devices within Intune. I have dynamic groups which group together 'Personal Work Profile', 'Corporate Work Profile' and 'Fully Managed' devices. This means items such as Company Portal are never pushed out to our Fully Managed devices (nor are App Protection Policies, which couldn't function without Company Portal) and they use separate Device Configurations.
The Intune app appears to have automatically deployed to our devices, despite not being assigned in the Apps section. Though users have said they're unable to log in. I have separately created another group with some of my test devices and assigned the Intune App to them (despite it already being deployed) and these test devices I'm able to log into the app, just not complete the registration. This may be coincidence, I can't guarantee that's how I got that far!