Issues inserting a window or door into a wall modelled off vertical or horizontal.

This problem only occurs if the wall is slightly off vertical. If this is deliberate, draw the wall as being vertical, insert the door or window, then move the wall node to give the required angle.

If the "off vertical" is not deliberate, use a snap greater than 100 mm. You should select to constrain the drawing movement to the horizontal and vertical and only remove the constraint when drawing walls that don't meet at right angles.