Inner counter being classified as open corner

[FlorianPircher]

See the following topic:

If the gap is too narrow, is it fill in?

That is a know issue. And the 4 is one of the very few places where it occurs. It has to do with the outside open corners. You can prevent it be selecting the to node of the inter nodes (the one that has the arrow pointing up) and run “Open Corner” from the context menu.