Greetings, Tenno!  The Nightwave Elite Weekly that required 40 waves of Defense has been swapped with ‘Kill 100 Eximus’ after we received bug reports of the 40 waves not counting in Orokin Derelict Defense. If you experienced this bug while trying to complete the Defense weekly, we're sorry for the serious frustration this caused. We’ve reviewed other challenges as well to help prevent something like this from happening again. We appreciate your patience as we work to iron out any bugs