Mesh Collider convex checkbox is incorrectly simplifying an object

Hello, I am having an issue where a simple object (scaled cube with a bevelled top edge) is not calculating its collider correctly when I check the convex box in its mesh collider:

This object is part of the collider for a ship in a mod for a game i am making, the game requires reasonably accurate collders made of purely convex parts. I took the visual model, simplified it as much as possible, and separated it into ~30 convex parts. The convex checkbox works for all of the hull pieces, but is failing for the mount/extrusion pieces. Which are all having the same issue

I have checked to make sure that those faces are not backfaces, all transforms are applied, and the vertexes are all perfectly in line, these are definitely all convex shapes. I have tried separating the top an bottom parts, no dice. I did just notice that the issue is also occurring on the front face of the ship (left side of the image) which is slightly bevelled as well.

Any help is appreciated!