(In reply to Dave Townsend [:mossop] (he/him) from comment #1)
Looks like CreateProfile never did set the default profile created as the default profile. It just happened by chance due to an old behaviour that isn't implemented with the new method of profile management. I'm not totally sure that making it always set the default is the right thing to do here.
I would agree that if there are other profiles on the system, using -CreateProfile shouldn't change the new one to be the default. However, I would argue that if there are zero profiles on the system, using -CreateProfile to create the first one should absolutely make it the default.