After landing the final hit on Calamitas, I opened my inventory while I had autopause on. After closing my inventory, Calamitas' 'corpse' stuck around for a few seconds, but it just disappeared without dropping anything.
After Calamitas' corpse dissapeared, the Boss Checklist mod displayed the message that displays when a boss despawns, but the message did not display the name of the boss despawned.
Singleplayer.
Windows 11.
I have a graphics card.
I have 16GB RAM.