I was wondering if anyone else has encountered this and has a workaround:
I have created a map with the javascript API which uses the basemapGallery widget. The default map is dark-gray, which has a max zoom level of 16. If the user changes the basemap to Imagery with Labels ("hybrid"), they still can only zoom to a max level of 16, and not to 19, which the hybrid map supports.
If I set the default map to hybrid, the max zoom level works as it should.
Setting the maxZoom when initiating the map does not make a difference.