So here is a response i received from support when i messaged them about a boss that wasn't spawning in a dungeon.
Greetings again!
Thank you for replying and informing us that Marbita has finally spawned today. As for the reason why it did not spawn yesterday, might just be shear coincidence as there is no report, as of yet, of an issue with this specific NPC.
Like I previously said, sometimes you need to kill the other bosses several times for the other boss to spawn, as I believe it is actually the way the boss spawning system works. If you wish, you can use the /feedback command and give your opinion about this system, as it is, it might need some twinking to avoid situations like yours.
If there is anything else I can do for you, please get back to me and I will do my very best to answer your questions and doubts.
Once again, thank you for your patience and understanding during all of this process.
Warm Regards,
Luis
The Elder Scrolls Online Team
Pay attention the part where it says you have to fight a boss several times to get another boss to spawn once. DOES THAT MAKE ANY GOD DAMN SENSE TO ANYONE? Seriously, i have to fight an NPC several times to get one to spawn. Its not as if they are all so easy to take down. I just got my arse handed to me by one name Emelin the Returned. I couldn't defeat her once, can't imagine having to do it several times. And that is a solo dungeon. If we have to kill the same NPC multiple times to get 1 NPC to spawn then that tells me that they need to fix their spawning mechanics. There has to be a better way.
Edited by djhuff23b14_ESO on August 7, 2014 7:00PM