Reproduction steps:
1. Open the user's attached project
2. Open "MainScene.unity" Scene
3. Enter the Play Mode
4. Open Window -> DOTS -> Systems
Expected result: Systems are shown in the Systems window
Actual result: Systems aren't shown in the Systems window and an exception is thrown:
InvalidProgramException: Couldn't find system $PostUpdateExampleSystemGroup in World
Reproducible with: 0.50.1-preview.2 (2020.3.37f1), 0.51.0-preview.32 (2020.3.37f1, 2021.3.6f1)
Could not test with: 0.17.0-preview.42 (2020.3.37f1) - Console error: Assets\\Scripts
MainScene.cs(67,36): error CS0117: 'ScriptBehaviourUpdateOrder' does not contain a definition for 'AppendSystemToPlayerLoop'
Reproducible on: Windows 10, MacOS 12.4 (M1 Max)
Note: Exception is not thrown in when opening Window > Analysis > Entity Debugger