A lot of people have the same issue; it seems the latest update has caused a lot of items from build mode to vanish. There's a thread over at EA Answers: https://answers.ea.com/t5/Bug-Reports/Clutter-items-not-showing-up-in-Build-Buy/m-p/14393957#M311140
Someone on the German Sims Discord has found this workaround: use the cheat bb.showliveeditobjects, then search for "debug". According to this user, it should show most of the objects that have disappeared. Alternatively, searching for an object by name seems to work as well. I hope EA fixes this soon.