After your hero has defeated their first nemesis ever in the Deathray Demolision quest, you are able to make a new one from talking once more to MCPD Captain Martin. After you finish creating your 2nd nem (or 3rd and onwards) you'll get a mail from Defender who has the Quest called Prison Break requesting you to stop a riot created by your new shiny nemesis. Once you enter the prison a short cutscene happens and you are attacked by a group of minions. Once you are done with them if you go left to check the security cameras in the console, you'll trigger a bug which by activating the cameras, your nemesis will become stuck forever and won't be able to complete the quest. The only known solution for me is leaving the instance and re-entering without touching the camera console.
@kaizerin
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Comments
More annoying is Bunker Buster. That's my favorite Nemesis mission and sometimes that one also fails to complete.