I like to better understand why in the following image I cannot fill the gap by adding a new segment or joining two adjacent nodes on each side. Basically after joining the gap remains. The only time the gap is filled is when joining all four corners, but then they all become a single node (pointing arrow) destroying the concept. None of the four corners are open nodes. Why is this happening and how to fix it?
PS: These are open paths as their end do not meet their start.