GOautodial Open Source Omni-channel Contact Center Suite

The calls/campaing that we are handling are inbound only.
When calls get in the queue, and if the agents are occupied, we play MOH, after 40 seconds have passed and all the agents are still busy, we play another message saying that all gents are bussy, and when they get status ready, all calls should be redirected to available agents.
The issue that we have is that a number of agents ready waiting for calls do not get calls that are in the queue, and they can be waiting for a couple of minutes before they get the calls from the queue transfer to them.