Azcapa's Medallion stopped dropping (I only have 5 medallion slots)

[NOT RELEVANT]
After killing the Architect I clicked on the "Azcapa's medallion" when I didn't have a slot for it. I wasn't shown any warning nor anything. It just disappeared.

The issue is that since then I have run the Architect multiple times, and it hasn't dropped ever since.

EDIT:
Was just getting unlucky needed to kill 13 more achitects :D