Hello,
For at least a year, my stairs and tympanums have been flying around when placed in the basements of buildings, sometimes making the stairs inaccessible to Sims. I initially thought it was a bug specific to one particular building, but I've since discovered that it occurs in all my buildings where I've placed stairs and/or tympanums and/or columns in the basement, as well as sometimes wall objects. Screenshots of the problem are attached. I can also send you my Tray files and videos.
