Something with loading in in addition to manifest armor seems to break the behavior of Sweep Attack procced by Shield Throw.
While playing in a party with a friend I discovered that although I am hitting my Manifest Armor with my Shield Throw it doesn’t proc Sweeping Melee Attack IF my friend is the first to enter a new instance. When I enter the new instance first everything works fine.
As far as we could test it doesn’t even matter who first leaves the old zone but rather who loads into the new zone first. As soon as he disconnects everything is working as intended again.
The bug is easily reproducible.