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I'm trying to model a spaceship and I ran into this weird predicament. I'm using a mirror modifier as can be seen and I get this annoying crease:
If I enter edit mode, you can see that the verticies are connected:
And adding mean crease doesn't fix much:
What's a good way to fix it?
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You have some non-manifold inside faces caused by the mirroring. Select and delete them with X or Del.