coach leaves for a few minutes

[BlitzkriegBob]

I'm not sure how you would notice an MIA coach during a live ball, but assuming you are using NFHS Rules:

Rule 6-1 defines a team member as "Team members consist of all school representatives located in the team bench area, including but not limited to coaches, teammates, managers, trainers and the players."

Rule 9-1-1 states that "All nonplaying team members shall be seated on the designated team bench during the set. The head coach may stand during the set in the replacement zone, subject to Rule 12-2-6."

However, there is no penalty for this violation. Personally, if a coach needed to go to the bathroom, what options would you have other than to let them go? Deny them? Issue a yellow card if they take more than a minute? Hold up the match until they get back? I'm not sure why you wasted three minutes. For me it wouldn't be an issue until such time as I needed said coach for a reason, such as submitting the next set's lineup.