The semi-circles on left and right seem to merge with the central circle. I'd say there isn't enough room for both threads of filament. And now it's printing that's what it looks like: the semi-circle is distorted inwards.
(Yes this is a bit of a thin wall in the original model so I'm actually surprised it sliced at all. But in reality the two semi-circles are guides for thin electrical cables to keep them out of the central cavity, so no need for any strength.)
