We have identified an issue if you set your PMR site admin setting to lock after 0 minutes and have this set for all users.
If you have a PMR Audio only meeting there is no way for the host to admit those users. You can press *5 to unlock the meeting but this does not admit those users into the meeting. They stay in the Lobby.
The attached image is the setting configuration that causes this issue.
These are set to improve security for PMR's