They posted in the TWAB a few weeks ago (correct me if I'm wrong) that if you had not finished the quest but Nov, 27, the quest was going to disappear and the Thunderlord would become a random drop. Now when they said it would disappear, I could have sworn they said it would be gone at reset and not this early.

You did it too late. Stuff is being removed and you'll be kicked off the servers until the update is done. Never wait until the last day to get stuff done as this can happen at any given moment.

I have the same issue. Although I was on step where you had to loot the sectors. The item just randomly disappeared. Seems like multiple people were/are having this issue. Huge shame. :(

I was just about to do the last part the cosmodrone but the quest is just gone I would have thought you have time till the reset to do it but its just gone