It shouldn't. I don't know what your "Persoon_Geslacht" microflow does, but maybe you can remove activities from there and from this MF one by one till your microflow works? What you're doing is a very common scenario (creating an object, do some stuff, then commit) so I'm somewhat skeptical about this being a bug in Mendix. It seems more likely that there's a mistake somewhere in your flow, but I can't conclude anything without seeing the entire flow :)