I can not insert a door or window into my wall. Is there a bug?
Not that we know of. If you put a door or window to close to the edge of the wall you may see this happen, try starting the window or door away from the corner. If you do want to add a cornerless window or door you can see this video.
Just so you know we made the functionality work like this for buildability reasons. To support a wall over a window you will need a Lintel or head and they both need something on both ends to support the weight.
If you do want to add a window in the corner there is an old video here yet there are better ways now, we will make a new tutorial on this topic her is the old video link youtu.be/Br4IJdm-ZNc