If you try to share a map as an application, and there is no longer an option to choose one of the various application templates provided by ArcGIS Online or other configurable app templates, you may need to reset your templates group.
Follow the below steps to correct this.
Click "Edit Settings"
Click the "Map" tab
Change the "Configurable Apps" Settings back to the Esri default.
NOTE: This will change your settings to the ESRI Group. You may also switch it back to one of your other groups if your admin already has a custom template group that should be used.
Click "Save" at the top of the page.