Same shader will not work the same in two different materials with same parameters

Hi,

I am trying to convert my InfiniGRASS system to URP. I have converted the shader succefully by adapting the Lit URP shader and works fine.

But for some reason the material imported from the original InfiniGRASS will not work if simply assign the new shader to it, even if it is exactly same as a new material i used in my test project while developing the new shader, with the exact same shader and variables that do work if a new material is created.

The old material with the new shader misses the transparency or alpha testing and shows as a non transparent quad (though the selection outline is like it has transparency in the editor and follow the grass contour and not the rectangles of the quads i see visually) and is generally totally wrong looking.

This is extremely confusing and probably some Unity bug that need to work around by making new materials and assign to all items one by one, though this process will take long time to finalize and i wonder if this may be a known issue and there is some solution.

Thanks in advance