If the visualization always displays in Tableau Desktop and periodically does not display on Tableau Server, I would guess this points to an issue with Tableau Server being unable to get access to these assets after the Viz is published. Where are these maps located? If they are hosted on Tableau Server itself, there is probably an issue with the client machine getting access to those assets because of permissions or a firewall or something else. This isn't an exact solution for your issue, but the root-cause is the same...check out the below knowledge base article:
Maps Do Not Display on Tableau Server
Hope that helps!