My material is using Two Sided Foliage. After updating UE the master material and all instances had a white overlay that I could not remove. I have spent days trying to figure out how and why my entire model turned mostly white.
I created a brand new material using two sided foliage and plugging in my base color texture with nothing else. It was still white when I applied it.
It turns out the default Subsurface Color was turned on and it was making the model white. I set a 0 value to it and everything went back to normal.