Lowering into spaces like that cannot be done from above the ceiling.
Each level of a house has a set Z-axis count (I believe is 16 - need to check that) from the floor below. Once an item goes above that Z-count, it is officially on the next floor and cannot be lowered if something else is occupying the spot - as in your sample pic (a pillar is occupying the placement spot).
And yes - it is this reason that some interior corner pieces are left out, or a 90-degree wall piece used in construction, so whomever gets the house can decide what they want to do.
Most times, I use a 90-degree wall for these places when constructing.
Sometimes using the circle of transparency (better in the CC than EC) will allow the raising of a wall into a spot from a lower level, but lowering from above the Z-axis limit I've not been able to do myself - and I try, believe me.