From the help file:
"When you join geometry in the Family Editor, you create a union between different shapes. In a project, however, one of the joined element actually cuts the other according to the following scheme:
Walls cut columns.
Structural elements cut host elements (walls, roofs, ceilings, and floors).
Floors, ceilings, and roofs cut walls.
Gutters, fascias, and slab edges cut other host elements. Cornices do not cut any elements."
And it is true. No, it was true. Today it started to do it the other way around: the floor cuts the column. What puzzles me most is that in the same project there are instances of floor being cut by the same columns. Even more, if I redo the operation, it doesn't yield the same result.
Is it a bug?
Did my file get corrupted?