>for some reason
>any ideas?
it couldn't be more obvious anon

are there concave faces on the inner corners?

>>512946
Fucking Ngons.

>>512946
the mirror modifier should be first

>>512946
Using C4D for modeling id your problem, seriously.
Run, run away.
Install a proper modeler and import your stuff in C4D when needed

>>513009
I will expand.

C4D is amazing for a lot of reasons, but the modeling part is wonky, uncomfortable, tends to produce bad geometry and requires extra efforts compared to other modeling packages.

I was able to learn everything about the software including xpresso and complicated hierarchy setups in a few weeks and yet modeling was like the worst shit ever, even though I am proficient at modeling and did know exactly what I had to do.
In the end I had to give up and model what I had to model in Maya.

>>513009
>>513010
thats blender you retard.

There is a vert not in the center, so when you apply subsurf it fucks everything up. Check the clipping or whatever on the mirror modifier and move the vert over