@crinrictan outdated version of SNB Bills is the main cause of this. There may be other mods causing the same problems, but every time it happened to me, SNB Bills was the cause.
How the problem starts:
Have an outdated version of the mod in the folder. The problem start when the bills are delivered, the second after you get the notification, you can save the game, exit to the main menu, load back the save and reproduce the problem.
The fix:
Roll back to a previous save, update the mod, wait for the bills to be delivered, save in a new savegame and exit, load back the save and check that the issue is fixed.
If it's not:
Exit the game, remove SNB Bills completely, load the working save, enter the family and save the game again. Exit the game and put the mod back, this should clean up a save already affected before the issue happens.
