Hello. Thank you for contacting the Toolset support.
This is known to us and the feature is there but its hidden with some other maps settings. We already registered a ticket to improve the UI for this settings so users should be able to set the default map center when there is no marker available to display.
For now, the workaround would be, you will find the option to set a default center With your Maps block.
=> Check this screenshot hidden link
What you need to do is, You will have to disable the setting "Adjust zoom and center to show all markers at once" option on the map, in order to get a default center. Once you input the default center value, you can reactivate the option, and the center will be there.
Can you please try to use this workaround for now and try to resolve your issue.