Infernal Hordes can sometimes glitch in Season 5, resulting in no loot for players at the end.
Several players have reported that no chests appear at the end of the Infernal Hordes. SneakyStabbalot mentioned that after defeating the Council, the event glitched. When this happens, players can’t leave or teleport and must quit the session and reload.
Hopefully, this bug will be fixed in an upcoming hotfix.