I've been playing with PL5 on a couple of different installations under development and have run into a problem on one installation where the menu appears at the bottom of the page (and the menu is in the header section in the builder).
In fact everything within
<div id="site" class="site-wrap"></div> gets pushed to the bottom of the page.
I deactivated everything and the menu appeared where it should (at the top). I reactivated one by one and found that the problem returned after reactivating Yoast SEO.
If if install Wordpress SEO of Joost van de Valk complete DMS layout is broken in Chrome. Safari and Firefox are ok.