As everyone is stating above and as I stated in your 3 other bug report posts.
Firstly, if you are looking to post a bug, you need to post evidence, send evidence in a CS report or PM it to me so I can see what you are talking about.
In this specific case, if you have WON and met the XP requirement, its easy, take a screenshot of you showing the win with the XP requirement and then the mission not being completed.
I tried to replicate this yesterday and again today (as I did with all the bugs you are saying exist) and did not have the problems you are saying exists, nor are the players that are commenting on this topic. The mission is not bugged as far as we can see.
HOWEVER, if you have evidence with screenshots then please present them. So we can figure out what this is. Just posting repeatedly that something is a bug without any evidence or a proper description etc does not necessarily explain the issue.