I've tried re-doing this like three times from scratch and no matter what, Vertex Colour never shows up in the input menu when I' m trying to use the shader. Have I missed a check box or have to enable something somewhere???
I had the same problem today. My solution was to enable the ''Node Wrangler'' Add-on. I totally forgot to enable the plugin.
Yeah dude haha, I jus ended up taking the time to fix all my faces up for subdivision. I ended up just using an attribute node with the UV layer on it which I think is the same thing anyway??? But when I started using shaders I had to enable node wrangler for shift+control click to apply the shader to the viewport and realised I needed it to use the input>vertex colours