Check and see if you remove the front door if that makes a difference. I noticed the door I chose for a particular build, causes my Sims to actually have to step down into the foyer. I only noticed this when a Toddler sat on their behind to get into the house, much like they do when on a platform. :open_mouth:
The only other thing to try that I can think of, is to level the lot with the lot tool. I do hope someone with more experience comes along with better ideas. Hope this helps. Nothing more frustrating than spending hours on a build only to find an annoying glitch near the end of the build.