Why does my furniture fall to the lower floor?

[Mrs Yak]

I’m building a modern house with a cantilevered balcony on the second floor. I’m having trouble with placing furniture because it wants to fall to the ground level. I have tried putting columns under the balcony , rebuilding the balcony, and building a room under the balcony but am still having the same issue. Has anyone else encountered this and figured out a solution?
TIA

[Mrs Yak]

Update: I uploaded my build to my library and placed it on another lot and the issue resolved itself.