Operation Guillotine keep getting one hit killed

I started playing the campaign again today and when I got to operation Guillotine and got to the point where I needed to start taking out the "MG Nests" it kept saying I hadn't taken the second one out and I had. I got around it by just continuing the mission though when I pause the game it says it is still one of my tasks. Once I got to the point where I needed to use the Javelin I started getting instantly killed by one shot from a random NPC. After getting past the part with the Javelin I got towards the building and now when running in front of the stairs (no cover) to the next portion of wall I keep getting killed no matter what. I keep having to restart from one checkpoint and there is absolutely no way to continue does anyone know whats happening?