When BPS is trying to place a building, it'll use the full building extent when checking for what it can place. Eg: I can over over the corner of an 20x20 building (playing pyanodons) and it'll put that building in.

But for placing modules, it'll only check the center of the building, so I have to hover near the center of that building.

In vanilla this doesn't matter of course, biggest building is the rocket silo. But Py uses a lot of huge buildings where it becomes more of a nuisance.

Obviously this is VERY minor issue.