Master material displaying differently to regular material with same inputs

I created a master material to be able to vertex paint snow onto meshes with parameters for things like different base colour, normals, roughness maps etc. With some of my materials I grouped up the roughness, metal and AO into RGB to save space and so I turn these on with switches. The problem is they look different in the master material to how they look normally if you had just made a regular material out of the maps, I’ll attach screenshots to illustrate how it looks along with the material inputs.

I can’t work out what the problem is since all the inputs are the same, is it an issue with how I turn the R/G/B channel maps on with a switch? The issue isn’t caused by the lighting not being baked as a re-baked it with the material change, it looks almost like one of the material channels is displaying incorrectly.