I suppose it's an interface bug on the mission start interface.
Had two Elite Strike missions today for 7500nethershards and 500war supplies. Both extremely easy to counter, as both started at -15% (last week it was -100%, I even logged out and back in to make sure it's not bug), Also nethershard mission only had one thing to counter and war supplies only had two counters.
It was pretty easy to get +130% with only one follower and I was happy for a while that those missions won't take all of my followers to complete, so I will be able to do other missions during these long ones aswell. How naive xD
As soon as I sent the missions I checked ''in progress'' tab and saw war supplies mission is having -60% and nethershard one +60% (but both were sent with +130%)
Made an ingame bug report, so hopefully it will not happen to too many people and get fixed asap, as I don't believe I would get the resources for it just by writing a ticket.