When checking the properties of a Runtime licenses via the License Manager, the Customer Project ID value is not listed. Is this the expected behavior?
Yes, it is the expected behavior.
The Customer Project ID value is normally only useful to the developers – to perform Developer installation of the SDK, to set up Engine initialization in the application code, to configure automatic Runtime installation of the SDK on the end user's side, etc. In other words, end users are not expected to need the Customer Project ID.
Therefore, for Runtime licenses, which are intended to be used on the end user's side, the Customer Project ID is not featured in the license properties accessible via the License Manager.