Sims 4 build/buy mode issues

Try right-clicking on the game in Origin and hit repair game.

Are you using custom content or mods in your game ?

Hm, 

maybe you have a corrupted save then

Try the solution here: http://answers.ea.com/t5/The-Sims-4/SOLUTION-Savegame-was-saved-with-a-newer-version/td-p/4205460/

try erasing your saved games, this worked for me and I hade the same issues as you did.