Sounds like they lost their motivation. This could be due to *many* different causes, some interpersonal, some not. It’s a hard thing to get good, consistent, dedicated work out of people who are basically volunteers or very low on the wage scale, unless you can invest in them the feeling they have a personal stake in the success or failure of the project.
Assistant jobs like this were always touted as the first step in an ever-upgrading path of post jobs. So my question, if I put myself in the assistant’s place for a minute, would be: “when was the last time I got to do more than file tapes on shelves? When was the last time the editor took some time to teach me something, or even have me cut part of a sequence (under his supervision) for the experience? WHEN DO I GET A TURN TO PLAY?”
I am NOT suggesting you are running a sweatshop, by any means, but it’s good to occasionally put yourself in the perspective of the other person to see if this arangement is still mutually benficial. The barriers to entry are so much lower now, you can’t always expect the same kind of dedicated low-level peon type to stay as patient as they used to… they can just go out and buy their own system and practice at home without you… and undercut your rates!
You gotta let the waterboy practice throwing passes every once in a while, or they end up spitting in your Gatorade when you’re not looking.:-)