Why does Unreal keep loading sublevel before loading screen?

I emptied my persistent level (“Apartment1”) of all actors and added all geometry to sublevel3 and the lightmaps for day/night to sublevels 1/2 (as lighting scenarios).
I have set up the level blueprint to the best of my understanding and based on tutorials, now I would expect it to load+show the InfoWidget as loading screen before starting to load the sublevels. However, everytime I launch my build, the screen goes black for 7seconds, then the Info widget is loaded almost simultaneously with the geometry and the lightmaps (that are on sublevels).
(All my levels are saved in the content folder, none under content/maps, but I don’t think that would make a difference.)

Is there anything set up wrong with my blueprint, or does someone have a clue?
I am using 4.21 on OSX and building for Mac.