I have added a function to a blueprint interface, but I'm not able to Set this function in a different blueprint. Why?

Thanks for the reply. Unfortunately, I get the error “Only non-interface events can be converted to functions!”

BTW I am following this tutorial : The ultimate guide | How to Save & Load your unreal engine 5 game | ue5 (youtube.com)
And you can see he is able to do it without issues (from min 23:44).