Steps to reproduce:
- Make Material Function
- Make Material Collection Parameter with some Vector4 parameters
- Reference the Materical Collection Parameter in the Material Function, choosing several different items
- Save the Material Function
- Re-open the Material Function
- The Material Collection Parameters have all reset to the first one in the Material Collection Parameters list
E: I am seeing this in the regular Material too, when tested. Is the Material Parameter Collection node just broken in 4.11.2?