I was just tooling around getting used to the fact that they’re only showing in game view and… suddenly they’re working in scene again. I didn’t change anything or do anything, it just started working. Your guess is as good as mine
If you aren’t seeing entities in the Scene View but you can still see them in the Game View - open the Preferences window (Edit > Preferences…) then on the Entities section, make sure “Scene View Mode” is set to “Runtime Data” not “Authoring Data”
Seems this should be added to the Unity Manual for 1.0+ as this is not immediately apparent to people trying to transition to ECS now that there is a full release, thanks for the solution.
I too, had this problem recently. I think the error should also popup in the editor. Why singleton was loaded fine in the editor is still a question for me.
In Unity Editor 2022.3.X, from menu options go to Edit → Preferences → Entities → Baking.
Click the dropdown menu and change Authoring Data to Runtime Data.