Hi Jan,
A bit of an unusual design in my opinion. Typically, the NewEdit page is shown in a pop-up and the ListView is never hidden. I’m not sure if this is some sort of bug from Mendix, where it doesn’t handle properly the Listen To functionality whilst hiding the dependant List View. Might be worth raising a ticket?
In the meantime, I would actually consider changing your design. As a user, I find it a little bit strange that the Supplier Information of a previously selected Supplier still shows on the right, after I’ve clicked to create and edit a new one. You could either:
Cris
Maybe a bit more data-unfriendly way you could try: reopen/refresh the page in the same microflow where you save the new object?