Hey Steven!
Meraki Go APs will default to Gateway-mode, but they'll come online as repeaters for one of two reasons;
Either the physical connection is currently failing between the AP and its connected switch port, or the AP has been unable to obtain an IP address to reach the Internet through its upstream device and reverts to a mesh connection.
Please feel free to create a case with us via the app if you have trouble locating a solution to bringing your APs online with the physical connection.
Cheers,
Dom