Steps to reproduce:
1. Open the attached project (case_1220015.zip)
2. Enter Play Mode
3. Select "Test" GameObject
4. Check either "Do Load Scene In Play Mode" or "Do Load Scene Async In Play Mode" in the Inspector

Expected result: An exception is thrown that the Scene could not be found (full path is required as per API)
Actual result: Scene "Test" is loaded without any objects present

Reproduced in: 2018.4.17f1, 2019.2.21f1, 2019.3.2f1, 2020.1.0a23
Cannot test with: 2017.4.37f1 (Required functions not available)

Note:
- As per API, the full path to the Scene is expected:
https://docs.unity3d.com/ScriptReference/SceneManagement.EditorSceneManager.LoadSceneInPlayMode.html