I ask this because, the other day, I downloaded it and played as General Raam and the game wouldn't let me go any further after the very first portion.  I reset to my last checkpoint and the game went along smoothly.  I ran out of time when I had to take out those seeders with the Boomshot and didn't play it again until last night.

I decided to restart the chapter.  I got to the Raam portion and the game wouldn't trigger the NPC actions at the end of the first portion, again.  I replayed that portion AT LEAST five times and it still wouldn't let me by.  I wound up turning off the console and googling the problem (with no results) and playing Mario Kart 7 instead.

Anybody else finding a lack of polish with this DLC?

I had no issue with the DLC itself, except the part that after it's release season pass owners couldn't download it for free and many who had a season pass thought it was not included in the season pass and downloaded it..... Enjoyed the DLC but was to short for the price...

I had this problem, too. During the SP, not during MP.
I went a little around, went to places I haven't been and at the moment I decided to restart it happens: Myrrah talked to me and I could move on.

Problem solved.  Little bastard was hiding in a corner, not even shooting at me.  What a coward!  Anyway, I killed him and all is now well.  Thanks, man!