[Therion] Lox model walls all inside out when a scrap contains a loop

I cannot get a lox model to show the walls properly when I add a loop in my scrap. I've attached the files I have been messing about with to test this. There is one loop in the scrap sketch (created by line 9, the last line in the file). As provided this does not display properly in Loch. But if I delete that last line so that the the centre of the loop is removed then the loch model looks fine. Am I missing a trick here? I cannot split every loop in my caving into separate scraps (before someone suggests that). I have too many of them in my real survey data. Testing with the 5.3.8 build. Footleg