It appears as though parameters for downstream material layers are reverted to their default values and override states when an upstream material layer is deleted.

Steps to Reproduce
  1. Create three material layers with a variety of parameters (color, roughness, metallic)
  2. Create a couple of material layer blends, with a variety of parameters (direction, intensity, etc.)
  3. Create a simple layered material, and create an instance of that. Add your layers and blends.
  4. In the Layer parameters view, expand the blend and layer parameters and make modifications.
  5. Delete the middle layer.
  6. Observe that parameters on the top-most material layer and blend have reverted to default.

Alternately, see attached project for repro. Open M_MyLayeredMaterial_inst and delete "Layer 1" and observe Layer 2 revert to default values.

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ComponentUE - Graphics Features
Affects Versions4.26
Target Fix4.27
Fix Commit16120025
Main Commit16120030
Release Commit16120025
CreatedFeb 5, 2021
ResolvedApr 26, 2021
UpdatedApr 27, 2021
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