Heey! I found a bug on TFM.. in the survivor rooms, all the NPCs from the event were gone!

That is because you entered the room after the map started. You must be in the room when event map starts to be able to see the NPCs.

This is a known bug.

I don't think this is a bug
Event items (horseshoes,pots of gold,clovers) don't spawn in survivor rooms,so i think that's intended