First, thank you for your responses.
Here's what I'm seeing:
I have downloaded the SM Central Stalingrad map as well as the Railway Station, May we all be Heroes, and Restless Night files. The scenarios show up fine, and since these take place at 0200 and 0400 hrs, I conclude the map should show as occurring at night.
When I load them into the scenario editor, and change the parameter to "Day" and then launch the 3D Preview, the map still shows with a totally black sky--no stars, no moon. Nothing.
And when I load the Central Stalingrad Map--not a scenario, just the map--the same thing.
Yesterday, I had some luck with the Railway Station map in a quick battle map scenario and I was thrilled to see it launched in the daylight. When I tried to do the same today using the Central Stalingrad map for a huge quick battle, the map doesn't even appear as a choice to select from among all the other Quick Battle maps.
A perhaps related issue I see is that when I am prompted to select a map for a QB, the Bitvagorod map and at least one map I created for QBs do not populate the list for selection--at least not until I go back to the QB parameters window and select the "random" type battle. Sometimes I have had to repeat this a few times before I finally see the map(s) I'm looking to use (but never the Central Stalingrad master map).
Please give me your thoughts/suggestions.
Thank you!
Gonzalo