Alessandra

@Martindelataille for me this solution doesn't work, I have already set "standard group post" but the weird behaviour continue to be present

Got it...the problem is that when you create the parent folder you have to select "create new folder" in the Folder tree section of your content type otherwise this strange...

Maybe your case is different from mine..In my case by default I have "none" selected and not "create new folder". Have a look to your folder content type and check...