Blend vertex dynamic material

Hello,
I followed a tutorial about growing Snow on the floor.
It works, but only on models from Startercontent Architecture.
On all of my own models, which I made and imported from Blender, it won’t work.
They are just plain white with normals.
I tried exporting and reimporting the working one, which after importing aswell, only displayed white with normals.
What am I doing wrong there?
Greetings