FHei @stefan.schoeb, did you set this on your instance settings or on a specific organization? And did you click apply configuration after you changed the setting?
FI did set it on the instance and it works fine
F@stefan.schoeb did this work for you? In the call yesterday you said, that you only set it on organization level. If you have it on the organization and do not send a primary domain scope, it will not trigger on the userselection page, because we don't know which organization we should trigger.
FPerfect. 