I began experimenting with PBI's Composite Models last week while connected to my AAS Model and a simple Excel File.
Unfortunately, regardless of what December release version I have been on (originally on 2.88.721.0, then updated to 2.88.1144.0) I have experienced multiple prompts for my Windows authentication. When I first make the composite model connection, I am prompted 3-4 times to enter my password. This repeats again seemingly whenever I add fields from the AAS model into a visual. This also repeats when I try to create a relationship between my Excel table and one of my AAS models.
In total, this results in around 15+ password prompts (with additional 2-step verification codes) within a 5 minute timespan... Effectively making Composite Models unusable for me.