How to get shader compilers to tell me why they failed

I’ve posted this on the forums and the discord and have found no help so far, So we recently moved to 4.18.3 using the github source, when packaging a bunch of materials fail to compile but it doesn’t tell us why it failed and the material editor looks just fine and shows no issues.

we get this in the log for each material that fails, same output just different asset name:

UATHelper: Packaging (Windows (64-bit)): LogInit: Display: LogShaderCompilers: Warning: X:\FF-Git\Content\FF_GARAGE\Meshes\materials\lambert2.uasset: Failed to compile Material for platform GLSL_150, Default Material will be used in game.

How can I find out why some materials are failing to compile? This is all the output log is giving me and the material editor doesn’t show any problems

it tells you exactly why in that warning report.
GLSL_150 means it wont run on SM_4 (vulkan/high end mobile/html-ish related stuff)

if you open the material and enable stats you should be able to see which nodes are causing the issue.

Why would this fire when packaging to windows 64?

That I dont know, might be a wrong setting somewhere?