I finished the Torgue DLC on playthrough 2, and decided to kill Pyro Pete the Invincible to get myself some Seraph Crystals. I had seen many videos on Youtube showing him dropping a mess of them, and he seemed the easiest of the Seriph Invincibles to farm. I did the mission for Moxxi to spawn him the first time, killed him, turned in the quest, and returned to Pete's Bar.
I took the elevator down, spent the 8 eridium, and he did not hop down. The board was dark, and my 8 eridium was gone, but no Pete. I saved and quit, retried, and this time he did spawn. I killed him, and he dropped no legendaries, no crystals, and only 4 eridium.
Frustrated, I saved and quit, and tried again; he took my 8 eridium, and again failed to jump down. Of the next 20 attempts he failed to jump down 3 times, beat me 2 times, and the other 15 (when I beat him) he dropped no legendaries and no Seraph Crystals.
I was using my lv 61 Soldier that has completed the main storyline for ultimate vault hunter mode (playthrough 3) so Pete is not too hard to kill, but there is no point if he drops nothing.
Is Pete's refusal to drop Seraph Crystals due to my being 9 levels higher than him? Is it because I have not completed Scarlette's DLC yet? Do I have to beat Hyperious once first? If I have to beat Hyperious, can i di it in Normal Mode (Playthrough 1), or do I have to beat him in Playthrough 2?
What (if anything) can I do to resolve this, and start getting some Seraph Crystals?