How to reproduce:
1. Open the attached project
2. Open the "TestScene"
3. Open the "script" Script from the "Scripts" folder which is in the Assets folder
4. Change the Debug.Log string at line 11 from "Test1" to "Test2"
5. Save the Script and get back to Unity Editor
6. Enter Play Mode with the Console window open

Expected result: Console window outputs "Test2"
Actual result: The domain isn't reloaded and Console window outputs "Test1"

Reproducible with: 2019.3.8f1, 2020.1.0b3, 2020.2.0a5
Could not test with: 2017.4.39f1, 2018.4.20f1, 2019.3.0a11 (errors when downgrading the project), 2019.3.0a12 (License error)

Notes:
-The Console window will only output "Test2" after restarting Unity Editor or reimporting all of the Assets
-When all of the Assets are reimported an error message appears: "Error: Could not load signature of ProtoModel:Write due to: Could not load file or assembly 'runtime, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null' or one of its dependencies. assembly:runtime, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null type:<unknown type> member:(null) signature:<none>"
-The mentioned error doesn't seem to occur when launching a fresh project but only after clicking "Reimport All" in the Project window