@SimGuruNick I was able to recreate this on three different lots in the linked save (this is not where I originally had the problem). I did have MCC and one other small mod in my game, but before I recreated this issue I removed them, deleted my localthumbcache and repaired my game (I didn't have either when I originally had this issue). The lots in question where you can see the terrain issue are The Blue Velvet, Arid Ridge and Slip 42.
With Arid Ridge, the block with the problem is one where I built the 'block', raised the foundation and then added the basement to part of that block. The block with no issues I built the 'block', added the basement and then raised the foundation. Both Blue Velvet and Slip 42 have buildings so you can just see the impact of the partial basements I added. I did not try the work around on either the Blue Velvet or Slip 42 lots in this particular save. Also, I wasn't able to extend the basement of the Blue Velvet to the edge of the building on the street, the build 'line' turned red and the game wouldn't let me. I had this problem in another save when I was first testing it out.
Also, I renovated the Goth's lot in this save (I did that on the weekend and at the time the two mods were in my game) and had added a basement which was within the main floor's floor plan (this includes porches). I just went back in to see if it had an issue with the terrain if I extended the basement and I did (I dragged the small basement to be at edge of the porch). This isn't showing in this save as I thought to try that after I had zipped and uploaded the save to my One Drive, but you may be able to recreate. Let me know if you would like me to resend the save with that done.
https://drive.google.com/open?id=1UlLmYQ6Icc_Jx9XWaTixNXWjOUyTYXJR
Best regards,
Jennifer
