I understand why this is happening. Depending on the point you pick on the drawing, the shape is either open or closed. But if you pick a point ‘within’ the spiral, it is closed. How do I tell LB this?
One work around is to take the spiral back to GIMP. Bucket fill it, save as png, import the png into LB and then trace that bitmap.
Looking at your file, I see 5 or 6 places that this shape is not connected to make a complete path. Entering ‘Edit Nodes’, I have been able to zoom in, grab one of the un-closed nodes and start to drag it away from its current location slightly then back to allow the node to ‘Snap’ to the other node.
use the select tool and deselect the object
use the nodes tool and click on a line in the object
this will select that segment which needs to be snapped to the connecting segment