[Edi]

LP, that could be WAD, but it needs some more clarification. Was the commander killed via a spell like Seeking Arrow or Flames from Afar that cause X amount of damage, or was it a remote assassination spell like Earth Attack that causes an assassination attempt?

The distinction is important since losing a battle in a province where a fort is being constructed will prevent resuming construction if the loss results in the fort construction orders being canceled. The most frequent occasion for this happening is somebody moving an army in before the fort is ready, in which case the province also changes hands. It would be easier to investigate if it was known whether the trigger is losing a battle or province ownership changing.