I have exactly the same error. I see the map in the overview as soon as I want to edit/add markers there is a white screen in the content area.
I have updated WordPress, updated the plugin, emptied the cache – still same problem. Editing the map is not possible.
Hello. Please try to temporary deactivate some other plugins. This issue can happen if you don’t have enough free memory on your server.
If this will not help, please provide us your current Free and Pro versions of plugin or contact us via internal support.
Expiring of PRO license shouldn’t block access to your maps or editing them. In any case, all pro features are still available after pro license has expired. The expiration of pro license regards only to support and pro updates.