I've applied all my other modifiers and applied all transformations and I'm just left with a Bevel modifier for my object. And this modifier is causing weird glitches at joints that involve faces with different materials (see that odd little rhombus of red at the bottom right):
I've got Outer Miter set to Arc and have Harden Normals ticked. I'm pretty sure there are no geometry issues (overlapping edges etc.). Using Limited Dissolve and Merge by Distance doesn't improve the situation and in wireframe mode, you can see the mesh is super simple.
With the Bevel modifier disabled, everything looks normal:
And if I set Outer Miter to Sharp, I don't get the look I want at the joints but the odd glitch goes away:
So if I don't want Sharp joints, how can I solve the odd glitch shown up above? What's causing it?
Any help would be much appreciated.
.blend file (created using Blender 3.1.0)...
And I don't believe it's an n-gon issue either. If I add and apply a Triangulate modifier (with quad and n-gon method set to Beauty) I still see this issue:
The faces above are all triangles and I've increased the bevel amount to make the "glitch" even more obvious.