As this issue has come up quite often, there's been little in the way of constructive information on narrowing the problem down. So I've gone through all 59 of my current saves, as I've had this bug several times now.
Google Drive folder for my Warhammer II appdata folder (everything but the save files are in a .7z archive): https://drive.google.com/open?id=1dOvEjvvuL2YwB8dOwYUKzCkdjPTd1DO4
Installed mods: https://steamcommunity.com/sharedfiles/filedetails/?id=1921803189
As for which saves show this bug, here they are listed by their turn number: 22, 24, 25, 54, 55, 56, 57, 58, & 59
To note is that this occurs for manual saves on the same turn as the autosave. So it's not the save file itself that is the problem, but the data being saved to it. These saves crash no matter how they're loaded; either from the main menu, after loading a save into the campaign, and after starting a new campaign.
I launch the game through Warhammer 2 Mod Manager, which can be obtained here: https://github.com/Kaedrin/warhammer-mod-manager/releases
The mods are sorted by their name. Screenshot: https://i.imgur.com/oO8YUCf.png
Warhammer II Build: V1.8.1 13089.1833768
My specs are:
CPU - i7 6700k @ 4Ghz
RAM - 2x16GB DDR4 3000Mhz
GPU - Vega 56
OS - Windows 10 LTSC 2019 x64 (Windows build 1809)
GPU Driver - 19.12.2