What I did was:
- Enable Ore Excavator to farm something;
- Take a furniture, I took that pumpkin light source that hangs, forgot the name (ESL speaker here)
- Tried to place it on top of those decorative cavern spikes
- Game CTD


My mod list is basically calamity, magic storage, expanded inventory and some other QoL mods that do not affect placement as far as I know.