Well I just noticed a bug with the side mission The Fallen. After a lot of searching I finally found the spot for the crashed Vråken.
From a distance I spotted a Hunter by the plane, seemingly guarding it. I snook up on the hill, set a good old fashion trap with gas canisters and a radio. Worked but wasn’t enough. So I ran to the nearby barn (close to the church) and took him out there.
A whole lot of his friends showed up and after using all my meds and all my adrenaline shots I spawned myself back in the church.
When I finally cleared all the enemies and ran back to the plane, getting right next to it this time, my next mission objective says “take down the hunter”… Took down another hunter close to the church, but the objective remains…
Took the loot out of the Vråken but no change.
Hopefully even this bug will be fixed in the upcoming patch!
I had that happen with the Gas something or other side mission. I was supposed to destroy a gas station. Well I did from a distance with the recoiless rifle. Then as I got closer it said my objective was to destroy the gas station that was already burning. Tried a few things but nothing worked. Then I thought to exit to the main screen then return. Sure enough the gas station was back again and I was able to destroy it this time after the objective came up and completed the side mission. This may work for you too as the hunter should re-spawn at the plane. Just wait till it tells you to take him out.
I have been back to the plane twice now. Both times the hunter is there and after shooting it a few times and running back to the barn the hunter disappears. The first time I went to the plane and picked everything up but the mission isn’t even showing on my list any more.
Disappears, as in despawns? The enemy AI is a bit wonky right now, they’ll target you from afar, or not at all. It sounds really strange, is there any way to record this happening?
@Zesiir, I think it wanders off. I did this last night. Specifically I was trying to pull that hunter up to the church, so I could pick it off from the belfry.
So, first attempt, I got it’s attention with a round. And then started booking it for the tree line. By the time I was halfway down the hill, it was gone. I looped back, and found it had lost interest before it reached the top of the hill and started wandering off. So, I proceeded to breadcrumb it with flares, eventually pulling it to the chruch, and picking it off there.
I didn’t see this, but I suspect, once you pull it off point, it’ll just look for something to amuse itself. So, it could just have, “gotten lost,” after it dropped aggro. If you want to move this guy to a better position, flares are a good way to pull them.
I’ll try that then! Thanks a lot! 
