Conquering castle bug in Sun Clan mission 4: the avenger

Hey, I got a special bug in the Sun Clan mission 4: the avenger when damaging the enemy castles below 1000 hp. First my Game and System Information:

GAME BUILD: Version 101.103.13286.0 (#144358) 18358599
GAME PLATFORM: Steam
OPERATING SYSTEM: Windows 10

When I damage enemy castles below 1000 hp to conquer them, something weird happens: the castle remains for Liu Biao’s Navy (Blue) and Liu Biao is saying, that this belongs to him. Thereafter Sun Quan says, that we lost the last remaining castle, meaning the castle which I tried to conquer, didn’t even count as conquered.
It’s quite the opposite: It brings the counter of the castles under my control to zero. Shortly after this, the game logically counts my mission as lost and doesn’t let me continue the mission 4.

FREQUENCY OF ISSUE
100% of the time

REPRODUCTION STEPS

  • Go to the campaign menu and enter the china (the three kingdoms) campaign
  • From there, select the Sun Clan campaign and from this one mission 4: the avenger (where Sun Quan longs for revenge to Liu Biao)
  • After that, open the mission normally and get some Lou Chuan warships at the docks via left clicking on them to produce them
  • Now left click the Lou Chuans and go strait to the castle northwest of the map with a right click
  • Move the mouse cursor to the said castle and right click on it, with the Lou Chuans, to damage and conquer the castle via lowering the castle’s hp to below 1000 hp.

EXPECTED RESULT: the counter of the controlled caslte going lower instead of higher, Liu Biao saying, that the castle belongs to him and thereafter Sun Quan saying, that we lost all casltes. Last thing: the typical defeated screen that happens if you’re unable to hold or finish the mission objectives.

Expected Result if the bug wouldn’t happen to me: the counter would go up with Sun Quan saying, that we conquered a new casle and thereafter, a normal game procession finishing other objectives like defeating Liu Biao.

Ingame recording to show the bug:

SAVE game file to avoid some steps:
theavenger5.aoe2spgame (1.8 MB)

I hope you guys can help me with this bug. Sorry for my bad english