Your comments

problem solved by enabling compile for the shader under Open GL ES 3.0

Thanks so much Joachim for such a quick answer! There's just a couple of more things I'd like to ask :

- what's the main discrepancy between vertex legacy and current rendering path, which is causing shader forge shaders to fail

- hypothetically, tying to first question, if I was to hand edit those materials by hand, what would I need to strip to be able to use them

- are there any plans to allow shader forge authored materials to work with legacy (I understand legacy is legacy, but I thought it's worth asking)