Beware of Alias settings Issues!
I was doing everything correctly according to the tutorial, and yet my dialogue wasn't working. I looked for hours online at solutions involving microphone settings, recording silence, creating custom voice templates, and nothing solved my issue! My NPC just wouldn't initiate the dialogue window and just sat there spouting default "his" and "huhs". The issue actually had nothing to do with my dialogue, but with an alias issue.
Here's what I did wrong.
I had created aliases in which the actors were "initially disabled" in their actor settings, but the aliases weren't set to "allow disabled" in the quest alias settings. This must have caused a feedback loop that stopped my quest from functioning whatsoever, including dialogue! If this has happened to you, be sure to set any initially disabled actors with aliases to "allow disabled" in your quest alias settings, and you should be good to go!
Hope this helps! (be sure to bump if you find this helpful!)
