Just putting this here in case anyone else encounters the same issue. Had a situation where some fires were burning in an area covered by a shield. After the fires were out there were "sparks" in the area covered by the shield, but nothing happened to them even in the rain and I couldn't do anything to the areas they seemed to rest in with a Pawn.

Unrelated, I found I couldn't fast forward past x1 anymore. Tried various things I read for FF issues including changing the Hold Fire setting on mortars, etc. Finally checked error logs and saw Shields were constantly generating a null ref at Shields.Shields.Comp_ShieldGenerator.WillProjectileBeBlocked.

Turns out sparks from the fire had been caught in the shield and held there indefinitely. Once I powered down the shield all the sparks fell to the ground and finally gave a notification for fire in the Home area. After addressing that I could finally fast forward again. Just something to try if you encounter the same.