Catacombs necromancer not spawning?

[armbars]

There's supposed to be one near the Great Scythe, but he's not spawning for me, which means I can't get the Skull Lantern early. Has anyone else had this issue?

[EF_Neo1st]

https://www.youtube.com/watch?v=JNtG1h2Eiuo
at 3:00 - 3:19

If you cant find him anymore and skeletons dont respawn, it mean you got the "lucky run" where he just falls to his death.
(and yeah, I dont know if both give, just one, just a % . . . ).