Borderlands 2nd playthrough bug?

So, I beat the game, and now I'm on my 2nd playthrough. I'm on the mission "Fixer upper", but every time I buy a shield the box doesn't check off! I read somewhere that to fix it, you have to join someone online that has the same mission. The only problem with that, is whenever I go online, it says my plot mission is "Find Steele". I don't even have that mission. It also says that on single player. Also! I have a ton of missions on second playthrough that I finished on the first. I didn't even accept them. They just showed up. Anything I can do?