They don't seem to have the resources to fix older content anymore. It's pretty much just the living story nowadays. The only way in is to wait for a daily that brings enough players to the map to create a new instance, try right after a patch, or get a port from a mesmer. Gosh really? That sucks. But would be nice to get an official announcement about the problem. As already mentioned from other people this event is necessary for Legendaries and it's really sad that we have to wait for good luck to finish them.