Any way to get cultists to spawn here?

[Voyager]

This is my old normal mode world. It had a dungeon that stuck way out of the ground so I removed the top.
The wiki says that this could mean I can't get the cultists to spawn

 

[652Graystripe]

I'd try defeating Golem first - if you haven't already; I believe you need to redo it post-1.3 update.