I can confirm the same crash on specific date happening, the game log shows a loop of
[character.cpp:16391]: characterName (characterId) becomes unlanded.
in the days before the crash.
The character causing this in my game were patricians of a vassal republic which had as only holding their house.
The top liege is feudal if that means anything and it might be since the game started having this problem when I, as the Lord of Braavos, enacted the law to become King