Hi Martin, I think that somewhere along the line the edges on the green part got divided up with one little teeny tiny squeezed one remaining. When I get rid of the magenta piece temporarily and just select all naked edges that should be bordering it from the green areas, it reads as 5 edges being selected. When I click them manually I only see 4. So there's some extra edge in there gumming things up. It may be possible to eliminate it using the merge command.

- Michael