Today I played around with 2020.1 for a while. As I mentioned in the 2020.2 forum already, good work on the performance improvements (link)! It's one step of many in the right direction. While playing a further developed version of the project from Case 1108597 in the 2020.1 editor, I noticed that sometimes additive scenes don't load. Code (CSharp): var asyncOp = SceneManager.LoadSceneAsync(sceneName, LoadSceneMode.Additive); while(!asyncOp.isDone) yield return null; When I tried to debug the problem and attached Visual Studio, the issue just magically vanished and Unity loaded those scenes, so I can't say if it's really related to LoadSceneAsync. But I can say that those scenes, such as the HUD, never made it to the Hierarchy Window and thus the HUD was never visible in the game. I was able to run around in the level, without loaded HUD and after attaching the Debugger, those scenes were magically added/loaded. There was also no error message. I know this report is rather useless for you, but I wanted to mention it.