Using Blender 2.91.2
I have a 'simple' two object model of a plastic go-cart wheel - an inner wheel and an outer 'tyre'. I have two different procedural shaders to simulate scuff marks on the wheel. The outer is more scuffed and gouged than the wheel inner.
Within Blender the two objects are correctly aligned, and look right in the Wireframe, Solid and Material preview.
No other settings change between the two renders apart from the choice of renderer.
Have I done something stupid ?
PS. My previous models rendered fine with cycles, so I don't think it is my copy of blender or my GPU.