Asterisk 1.2.14 Queue Agent member not ring, Queue not empty

I’m using Asterisk 1.2.14, from time to time, I get problems with the queue.
This happens once every few weeks while the queue isn’t empty, Asterisk doesn’t send calls to all the queue agent.

But all the queue agents have logged in. To solve the issue, all of our CS has to logoff and relogin as queue agents in order to proceed, all phones started to ring again.

Anyone experience this issue or know if there’s a bug in 1.2.14?