As it says, if the event is bugging out and the pact are frozen, and you are sure you’ve done both north and south re-enforcement quest chains.. pull mobs to the pact and get the pact killed, all of them. The large giant roaming around works best. Pulling him solo while having other players keep risen off of you while pulling him to the pact. Simply range the giant and keep all melee away from him.
Wherever the pact are stuck, find a way to overwhelm them with mobs.
He will yo-yo a few times as you pull him, but getting the pact killed often either resets them to their last check, or pushes them forward to the next.