Unfortunately I cannot reproduce this. I ran the application maybe 50 times. I get the basemap loaded everytime even though sometimes it takes a bit longer than other times. In this case, we are talking about some seconds but the tiles comes down even in high network pressure. Make sure that you have a hook on MapView.LayerLoaded and make sure that there are no errors there. Network might be one player in the game but at least for me, everything seem to work just fine.
Do you have any corporate firewalls etc that might be part of the problem?
Try to reproduce the issue while running a tool like Fiddler to see if you can see any errors / not returned tiles there and share the logs when you get the issue visible.