Now I have an answer. Actually, it made me grin, because I consider it counter-intuitive:
At clicking "Record", it does propose as recording profile 'default profile'. Though that is not the 'default profile' as can be found in 'Profiles', but the default profile that was defined and allocated on a user-based setting.
In case you don't follow:
In the profiles, there is a non-erasable 'default profile'. Checks.
You create new profile XYZ, and allocate it to that user. Checks.
User logs in, selects a broadcast, and finds 'default profile' as default, with profile XYZ only accessible in the pull down menu. The user is tempted to think, he had to pull down that profile XYZ for his recording. Does not check.
-> Because the 'default profile' shown as the default in the recording window isn't the 'default profile' from 'Profiles', but profile XYZ. Because it had been allocated earlier as default profile to the user.
Therefore it doesn't matter, if the user leaves the 'default profile' as recording profile, or pulls down the recording profiles to access and select XYZ; the recording is ALWAYS done with profile XYZ!
(If someone asked me for "What is a confusing piece of software?", I'd point to this one.)
Technically, my question is solved. However, I still think that a small change of the code is indicated in order to help users across this unnecessary step, and offering two 'different' profiles to select from.