Yeah they are all marked completed in triumphs.

And that’s the bug. Running invitation mission on legendary will erroneously mark off commencement too. So you can’t rely solely on the triumph.

Apologies I re-ran the commencement and got them. Thank you very much, and I was not aware of that bug.

As mentioned though, this is probably what is going on. Commencement can sometimes get marked off in the triumph box but not actually completed. Start by running that. Then head to the Altar and see if the armor is there afterwards.