Nothing changed in this area recently. There are a few ways to end up in a scenario where the boss doesn't drop an item.
If the fight lasted 20+ minutes, then the boss escapes. No exp and no drop in this case.
If the party leader DCed and took a while to disconnect from the server, then there wouldn't be a drop request because only the party leader sends this (with some exceptions on Ephinea like Rappies and Boxes).
The boss's death can often desync. If the party leader is dead and returns to P2 in the cutscene, there can be a rather large window where the other players finished the cutscene already. So other players finished the cutscene and boss is dead, then host DCs or returns to P2 before finishing the cutscene, no drop.
Was it one of these cases?