Would it be possible to integrate the group settings and map settings in: .....maps.arcgis.com/home/organization.html? We believe it would make it more intuitive.
We saw two clients where the group settings were correct for both, but still for one client one configurable app did not appear in the 'Create a New Web App' carrousel, although it was available for both under the group templates > View Application. It appeared that the map settings were not set correctly for this client and therefore only the ESRI apps were available. Our suggestion is to make it clear - when you set the group settings - that you have to check the map settings too since otherwise the configuration apps may not appear in the 'Create a New Web App' carrousel.
and it is explained here in two sentences. It took us a while to find this out, so perhaps an improved explanation, perhaps with screendumps would help too.
Group settings: For Configurable Apps, choose which group contains the apps you want to use in the group configurable apps gallery. Map settings: For Configurable Apps, choose which group contains the apps you want to use in the configurable apps gallery.