Where is the sun?

[SPCPapaJoe]

Silent Hunter 4 Steam edition with TMO 2.5 + RSRD. I'm on my first patrol, and for several days of sim time the sun has not risen. It's night all the time. I can see that the moon moves around the sky, but after it sets the stars stay out and it's pitch black. I had sunlight when I started the patrol, but that's about it. My gameplay style might be unusual. Normally I let the sim run overnight unattended at 1x or 2x time compression (to match how long a patrol would take in real time), then save in the morning, then close the game and shut down my PC to go to work. At night I load the last save and repeat. I've played SH4 like this for the past few weeks, and a week of sim time has passed since I left port. Has anyone else noticed this?

Side note: I've played SH3 + GWX for years this way and found that if I left the view on the map all the time I had a similar problem, but leaving the view on the control room fixed it-- no such luck with SH4.