Steps to reproduce.
1) Load save.
2) Dig with Ron Bloodletter agent in current location.
3) Game should hang. Mouse still works. I'm unable to switch to Task Manager or close the game via the task switcher. Have to sign out of Windows 10 to get the game to close.
Happened with different agent on different treasure map before.
Only started happening late game with treasure map clues I've seen before.