How to reproduce:
1. Open user-submitted project (PP_Multiple_Cameras.zip)
2. In the Addressables window ensure Play Mode Script is set to Use Existing Build
3. Build groups by clicking Build > New Build > Default Build Script
4. Open Main scene
5. Enter Play Mode
6. Select the CLICK_ME GameObject in the Hierarchy
7. Click 'Load Additive' in the Inspector
8. Click 'Unload Additive' in the Inspector

Expected result: the scene is unloaded without any errors
Actual result: "Invalid pass number (1) for Graphics.Blit" error is continuously thrown in the Console

Version testing focused on Post Processing package(all using Addressables 1.11.2):
Reproducible with: 2018.4.25f1(Post Processing 2.2.1, 2.3.0), 2019.4.4f1, 2020.1.0b16, 2020.2.0a18(Post Processing 2.3.0)
Not reproducible with: 2018.4.25f1(Post Processing 2.1.7)
Regressed in Post Processing package version: 2.2.1

Version testing focused on Addressables package(all using Post Processing 2.3.0):
Reproducible with: 2018.4.25f1, 2019.4.4f1, 2020.1.0b16, 2020.2.0a18(Addressables 1.1.7, 1.11.2)
Not reproducible with: 2018.4.25f1, 2019.4.4f1, 2020.1.0b16, 2020.2.0a18(Addressables 1.1.5)
Regressed in Addressables package version: 1.1.7