Me and a friend just tested this and it worked for both of us, I believe it must just be a bug with the new patch.
Basically you just use a Veteran Arid Skritt Cache that comes from the PvP SW Reward Track and it crashed the map and rolls back some progress for everyone.
Other veteran cashes from that track might work also but not 100% sure about that. Also I am not sure if this works on PvP and WvW maps, so if this works for anyone else please let us know.
Enjoy