This is the only mod I have, I am using the updated version, and my pregnant sims wear everyday, walk like they're pregnant, but don't have the belly. I was waiting to see if anyone else had this problem, but no one seems to... I've tried it with several different everyday outfits (including ones that worked with the EP3 version). Do you know what might be causing this?
I'd scan my downloads folder with Clean Installer, as this sounds like a hidden hack -- I just tested this (EP5 updated) with several Maxis and custom meshes that have pregnant morphs (both male and female) and got visible bellies every time.
I do seem to have one problem, though -- for some reason no one in the Greenman household can plan maternity. (The Roth family and the placed O'Mackey family both have that option, so I'm thinking it may have something to do with plantsims -- I'm going to download a plantsim potion and transform Morty or Gabe and see if the "plan maternity" option is still there.)
EDIT: Nothing to do with plantsims, Gabe O'Mackey retained the "Plan Maternity" option even after transformation and subsequent abduction. However, the O'Mackey household doesn't have enough outerwear to be able to plan that, and the Greenman and McGreggor lots do (Leod also can't plan maternity -- I made him over with a new bodyshape and thus he needed a completely new wardrobe). So it seems that when sims are able to plan outerwear, the option to plan maternity is overwritten in this version. (And if this turns out to be an unresolvable problem, leave it this way -- plan maternity only affects attire on community lots, while outerwear can potentially affect attire on any lot).