Held Ball
 

After a point the ball rolls toward the bench where the coach picks it up. They are clearly inside the "coaching area" but instead of returning the ball to the serving side, they hold it and step forward to begin coaching their team.

I understand that this could be a technique to "stall" the set or it simply could be absentmindedly. In either case it clearly breaks the pace of the set! Besides the R2 going over and physically retrieving the ball or asking the coach of they need a timeout, is there anything else that should be done in a situation like this?

Every situation is a little different, but I think if the R2 just said, "Coach, ball please, don't delay the match." It would solve the problem.

I've had this before. Being clear is the main thing that will aid you in this situation.

"Coach, roll the ball."