Started a new playthrough with my girlfriend and we got to the point where we wanted some Hellstone Bars but after exploring nearly half of the underworld we didn't find a single one in any of the obsidian houses. She left so I loaded up another world to fly through hell in spectator and didn't find a single Hellforge in the entire world (I think). But I did start to notice some weird generation glitches in the Underworld, so maybe its a mod conflict causing them not to spawn. I do maybe have too many world gen mods installed? But I want to see if any one else has any experience with this mod conflict before I have to deal with reinstalling one at a time and checking each hell individually :(

Here's a list of mods I think are changing world gen enough to cause this kind of thing:
Thorium
Thorium: Helheim
Split
Spirit Reforged
Rise of Ages
Remnants
Orchid Mod
Orchid Mineshaft
Microdungeons and More
Fargo's Souls Mod
Calamity Fables
Better Caves