This one is filed upstream, we'll have to workaround for now. The server asks helpers one at a time if someone wants to take a help request. If the user says no, or 20s has passed, it will offer the help request to someone else. This means if only 3 people let it time out rather than rejecting it, the user has already been waiting a minute for help. There is UI to change this timeout from 20s but it's not working.
Is this still a problem?
We don't currently have any need to change the agent timeout setting, so I'm resolving this for now as wontfix.