I have a master builder and an adept builder. I put both of them on the lift and it says "rebuilding the lift" but then after a few minutes they get up and walk away. I've tried and retried to put them on it but they won't do it.

I have level 2 restoration.

Thanks !

try another adept builder with them!

You should leave one of them selected and watch the messages you get. As Biddy alluded to:

Yes, you need.
Hope that helps