Is it a bug or wrong drawing?-Composite Corner-column inters

[Anonymous]

I draw a 29 cm. composite exterior wall.

it is :
-3 cm ext.plaster
-5 cm insulation
-19 cm brick wall
-2 cm inner insulation.

3 cm ext.plaster and 5 cm insulation covers all façade. when i turn the wall around the column there is a hidden corner intersection. is is a wrong way to draw or is it a bug? i draw lines to corners to get the correct 2d view.

[Anonymous]

here is a different corner intersection problem.

[Anonymous]

i draw lines to correct it
what is the problem/solution?