@Anonymous
It could be that the vertical extents of the section do not cross with the lower floor(s) therefore you can't see it on the plan view of those levels.
To check and rectify that, place a perpendicular section to the one not showing or go to a leteral elevation view >>> select the section >>> and drag its limits to cross with all floors you want to see it in
Ps: make sure in visibility graphics under annotations categories tab >>> sections are checked visible
