Also keep in mind that in game you dont have lumen enabled but in UEFN you do (High setting enables lumen iirc), which is why without a post process volume you see a difference.
Yeah I think this is at least part of the reason you’re seeing differences between editor and game. In editor, High scalability and up will enable Lumen. In game, it is a separate toggle that I believe you can only change from the front-end lobby.
Keep in mind that if you do disable the TODM, we’d generally recommend using the Environment Light Rig instead of loose light actors. It will provide you with the same auto exposure correction based on scalability that the TODM provides. If you still want to use loose light actors, then that scalability functionality can be placed using the LumenExposureManager.
I’ll need to talk to a colleague about the volumetric lighting and black ceiling.