I have to select profile twice when firefox is configured to ask for profile on start

[genodeftest]

Steps to reproduce:

1. have firefox configured in a way that it will always ask for the profile to start if you start a new instance¹
2. run firefox, select any profile
3. from sandwich menu select any other profile

What happens:
I'm being asked which profile to start.

What should happen:
In step 3 I already chose which profile I want to start. There is no need to ask me twice.

¹ to achieve this, run firefox --new-instance -ProfileManager² and uncheck "Use the selected profile without askin at startup". Alternatively you may set StartWithLastProfile=0 in section [General] in ~/.mozilla/firefox/profiles.ini²
² commands and paths on Microsoft Windows differ.