If you create a parameter collection node in a material and select a
parameter from the drop down and then copy and paste that node a _1 will be
appended to the end of the parameter collection variable name. Decal Mask_1
doesnt exist in this material parameter collection so I imagine that this
material would compile incorrectly.
[image: Inline image 1]
Create a material parameter collection, add a parameter.
Create a material, add a collection parameter node that points to that parameter
Copy and paste the node, note that the node name and parameter name should not change
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-43159 in the post.