Have beaten campaign, did not get Mark IV

I did beat the campaign on legendary difficulty, I played about 4 missions solo and 4 missions in co-op. While I was doing this I was not connected to xbox live. Is that the reason why I haven’t recieved the Mark IV armor yet?
When I look at my stats on the halo waypoint site, it says I haven’t completed any campaign mission.
What should I do?
Do I have to do the campaign all over again? …

Yes, you must be connected to Xbox Live to earn the armor, because the thing is based on Waypoint verifying the completion or something like that

Either way you have to beat the campaign solo for the helmet

You unlock it based on your commendation progress. If your commendations say that you haven’t beaten the missions on legendary, you won’t get it. You may have to do it again unfortunately.

Does the campaign have to be played chronologically to unlock the armor?

Oh, that’s a pity
I did get the all of the achievements for completing the missions.
The only one I’m missing is the one for completing the campaign on legenday, on your own.
But allright, the only solution is to do it all over again.
Thanks for helping guys!

That’s because there is no Mark IV. It’s Mark VI.

But you do have to beat it connected to XBL to get the armor.