WordPress Plugin "WP Google Maps Pro" Extra field are not adding

I'm trying to add Extra field in WP Google maps from settings But when i click on add more, It doesn't show up any input field only Remove and save setting button appears

When i click on Remove button removed, and if i click on Save setting , Page refresh and pop up appears setting create but field is not present there

Can you guide me how can i add Extra field in the WP google Map Pro

Thanks in Advance

via Chebli Mohamed