I'm having the same problem with vanilla bosses even, tried spawning EOC and king slime and neither of them showed up

the same happens to me too

im having the same issue

I don't know if this counts as the same issue (or is really an issue with the mod), but earlier I played some Calamity with a friend, we had Boss Checklist on. It started raining slimes, then king slime appeared. Upon killing him, he respawned again, and did it about 4 times until I died. It didn't even mark the boss as completed in the checklist, nor did it show a "King Slime was defeated" death message.

Also happens without calamity. Playing with Fargo's Mutant, Fargo's Souls, and Vitality. King Slime failed to spawn after slime rain, and through server commands / HERO's.

Disabled Boss Checklist and it spawned in fine. Not sure what could be happening, will provide any files if they're helpful.

For me everything was fine until going to fight Giant Clam. Whenever it spawns the healthbar appears but game freezes - i can't do anything (can't even open inv, but the animations are still going). At calamity forum people pointed out that if you disable this mod (boss checklist) everything works fine.

also having a issue with this mod rn, bosses wont spawn when its enabled. mod makers please fix

The bosses wont spawn, it says it does about 5 times but doesn't spawn it. But when i Disable it spawns just fine

Reminder guys that repeating the same bugs over and over isn't going to help anyone. There has been at least five updates over the past few days, the mod creator is actively trying to fix these issues but it's not something that's just one and done. Please read the comments because they've been giving updates.

its not just calamity tho, even in the fargo's mod boss summons it is already a known issue

wait is this 1.4.4 problem or has it been resolved.

still a bug, pretty much to my experience giant clam, frost moon, old ones army, pumpkin moon all freeze when there's a boss for some reason.