The guide advises that Pelotrio's ritual effect ignores Lucerna's, however the ritual is not spawning anything while Lucerna is active in the area.

Have you confirmed it works without Lucerna being present?

I think it was a mod interaction. I have updated several other mods, and now it works. Unfortunately I'm not sure what mod it was that was interfering.

At the time it definitely worked without the Lucerna active.