Mayhem Mode Unavailable

All campaign mission are complete on my Lvl 50 Zane, but instead of the Mayhem Mode selector in Tannis’ office, the Eridian rune slab is still there. I want to access Mayhem, but can’t. What do I do?

Other side of the ship, in the little alcove before Hammerlock’s quarters.

Thank you so much, you’re a lifesaver! :smiley: