After checking logs, it seems the interesting one is !Main log.txt (excerpt):
23:48:21 (Reporting) TFaction.LinkingInterdicted Union Sea Interdicted 1123 > 750 by 1348 Mississippi Mouth
23:48:21 (Reporting) TFaction.LinkingInterdicted Union Sea Interdicted 1123 > 1122 by 1348 Mississippi Mouth
23:48:21 (Reporting) Host MakeStep
23:48:21 [Error ] THost.MoveGroups Exception caught: Indice de liste hors limites (0) 1003185 Northeastern Virginia Army
23:48:21 [Error ] THost.AbortProcess Hosting aborted while performing MakeStep:MoveGroups 1
23:48:26 [Error ] TGameSim.RegionInFoW Undefined current faction
23:48:26 [Error ] TGameSim.RegionInFoW Undefined current faction
23:48:26 [Error ] TGameSim.RegionInFoW Undefined current faction
23:48:26 [Error ] TGameSim.RegionInFoW Undefined current faction
23:48:26 [Error ] TGameSim.RegionInFoW Undefined current faction
23:48:28 [Error ] TGameSim.RegionInFoW Undefined current faction
23:48:28 [Error ] TGameSim.RegionInFoW Undefined current faction
and on and on.
If needed I can zip and send the save + logs tomorrow, let me know!