I have setup a Queue in FreePBX. I have the retry option set 1 second, so if someone is in a call, they put the phone down and their phone rings with the next person in the queue.
This works just fine if I dial the Queue direct. If I get to the Queue via an IVR, the phone doesn’t start phoning with the next caller.
This isn’t a solution, but maybe a work around… I setup time groups and then time conditions, so if between the hours of 8-5 the call goes to the queue and if after 5pm the call goes to the IVR. Hope that helps a little?