OK I'm not saying there isn't a bug, but I did the mission twice and I made a tutorial you can watch here: It does have some good tips.
On this mission stay stealth, do not shoot unless shot at. Complete the drop off and get out of the area by ending mission. watch out for minefields.
https://www.youtube.com/channel/UCwe...1_CdFU_Mw4-SrQ