I have found a potential bug with the iOS Meraki app.
If you try to edit a switch port configuration on a port that have 802.1x set as the access policy then any changes you make cannot be saved, you simply get stuck in a loop of pressing the save button and nothing happening.
Your only option is to discard the changes and make them using a web browser. I suspect its because access policy settings are not visible within the app.
Hoping one of the Meraki team can shed some light otherwise I will open a support case. I have a video of the issue if required.