Ok, seems the fire part remains problematic in v18 (haven't tried to recreate the above yet).
Fire on ChopShop
This happened on the ChopShop map (config:0, danger 3, 3 party members, Vi). When the fire grenade was thrown it made an unusual graphics and an enemy going through that was not harmed at all. When it's the turn of the last combatant on the queue, the game freezes.
The log says:
BattleControlScript.SortCharacterScriptListByInitiative. Method called. Number of characters in list: 15
CombatQueueManager.GenerateCombatantIcons. Method called. PRE GEN. Current list display objects: 6 combatant icon scripts: 6
CombatQueueManager.GenerateCombatantIcons. Method called. POST CURRENT TURN GEN. Current list display objects: 1 combatant icon scripts: 1
BattleControlScript.GetCharScriptListPositionsForPostTurnPortraits. Method called. Number of portraits requested: 6
BattleControlScript.GetCharScriptListPositionsForPostTurnPortraits. Method called. Number of portrait positions returned: 6
CombatQueueManager.GenerateCombatantIcons. Method called. POST ALL TURN GEN. Current list display objects: 7 combatant icon scripts: 7
CombatQueueManager.GenerateCombatantIcons. Method called. POST GEN. Current list display objects: 6 combatant icon scripts: 6
NullReferenceException: Object reference not set to an instance of an object
at TileScript.ExtinguishTileFire () [0x00000] in <filename unknown>:0
at TileScript.ReduceTurnsOnFire () [0x00000] in <filename unknown>:0
at MapDataScript.ReduceFireTileDuration () [0x00000] in <filename unknown>:0
at BattleControlScript.EndTurn () [0x00000] in <filename unknown>:0
at BattleControlScript.EndCharacterTurn (Boolean requestedByPlayerIn) [0x00000] in <filename unknown>:0
at CharacterMovementScript.InvokeEndCharacterTurn () [0x00000] in <filename unknown>:0
It's also possible that there is some issue with the facility map. I've seen the regular fire effect on the china town map.