Bug Ritual altar on map

Hello,

I launched a map in corrupted Tier 15 with several modifiers active on it and towers boosting them.

However, I encountered almost no monsters and the ritual altars were missing.

So I was wondering if this was a simple bug or if there was an acceptable boost limit and different mods on a map beyond which there was a risk of counterproductivity. I hope I don't encounter this problem again in the future.

CloudKiller