I have just started a new league using the mods available here. I get through free agency and training camps, but when I get to preseason, I run into an issue. I've tried 2-3 different setups now and everytime I go to sim preseason week 1, it just locks up. It says simming and has the dialogue box in the middle, but never moves. This last one as been "simming" for 25 minutes and still won't advance.

It would help to identify each specific mod your using and the type of league setup. Don’t suspect that the real world mod is the issue since only changes names and graphics. Have you tried running without mods and does it work? If yes, then install one mod at a time and run to see if works. Keep adding each one until it fails, then will give you clue.

I found the issue. I had set the penalty for cutting a player to 100% of their salary, trying to emulate the real NFL where there are cap hits. For some reason, that made it just never sim. I'm sure the logic was trying to figure out who to cut in preseason to get under the cap.