Getting past a musicians ego
Don't quite know what you mean by ego? Most creative people have egos and desire to get up on stage and perform demands a bit of that so maybe allow them an ego to get things going. They can do something you can't do which is the music and performance. Maybe you need to get in there and do it for them. Offer to record a live show..mix a track they already done or hang out at rehearsal. You probably need to get some evidence of your production techniques so spread your wings and take any opportunity to get in on a session cos really you learn from experience.