Landscape Material - Layers sometimes not visible

Hello,

I’m currently having an issue with with the UE 4.16 Landscape tool. I created a master landscape material, created an instance of it and applied it to a landscape some weeks ago and everything worked fine.

Now I created another landscape to test some other stuff and the same material instance as well as the master material, which worked perfectly fine on the first map, won’t show any layers in the paint tool.

Now I’m stuck and can’t continue working with landscapes.
Any idea how to fix this?