@fozzieflipper, While I don't play with CC in Mods in The Sims4 (for this very reason ☹️ ), I did use CC in TS2 and TS3, but the removal process is different than what I had to go through for those. But here is a link that explains how best to go about it for TS4. I understand the 50% Method (located about half way down the page) is the key to this process, but it is best to follow all the instructions above that. It is tedious, but this is supposed to be the easiest way to go about it. 😉
Here is the link: http://modthesims.info/wiki.php?title=Game_Help:Finding_Problem_Custom_Content
You could also try to repair your game through Origin, and then if the Willow Creek houses still disappear, then try temporarily removing your CC. But from what I've seen in most cases most problems are CC/Mods related anyway.
Best of luck, and please update us on your findings! 🙂