Message says meeting in progress when there is no previous meeting in progress

[Resurrection1]

Hello, 

One of our groups is having issues joining their zoom meeting. When the host tries to join, they receive a message saying that a meeting is already in progress, when there is no previous meeting in progress. A participant does tend to join 30 mins before the host. Would this cause an issue? We tried deselecting the option to allow participants to join anytime, and yet the same message appears. Would setting up a waiting room help prevent this? Thank you!