Reproduction steps:
1. Open the user's attached project "AssetBundleWithShaderBug-Modify.zip"
2. Open "SampleScene"
3. Open "Editor/BuildAssetbundle.cs" and change the BuildTarget in line 82 to the current platform
4. Click "CustomTools/BuildAssetbundleForTestBug" in the menu bar
5. Observe ObjA and ObjB in the Hierarchy window

Expected result: ObjA's Material is using "Unlit/ShaderA", ObjB's Material is using "Unlit/ShaderB", shaders "Unlit/ShaderA" and "Unlit/ShaderB" are listed under the "Two Shader Refs" component on ObjA
Actual result: ObjA and ObjB's Materials are using "Standard" shader, shaders are missing from the "Two Shader Refs" component on ObjA, ArgumentNullException is thrown

Reproducible with: 2019.4.21f1, 2019.4.36f1, 2020.3.29f1, 2021.1.0a7, 2021.2.12f1
Not reproducible with: 2019.4.20f1, 2021.1.0a6
Could not test with: 2022.1.0b8, 2022.2.0a4 ("Unable to open archive file", "Failed to read data for the AssetBundle", "NullReferenceException")

Note: Regressed versions match the fixed versions of case 1178737 and case 1289806