For anyone having trouble loading Crystal Isles with the latest version. There is a typo in the maps.json file. Once fixed it works.
{
"MapName": "Crystal Isles",
"Filename": "crystalisles.ark.ark",
"ImageFile": "map_crystalisles.png",
"LatShift": 48.687,
"LatDiv": 15882.02,
"LonShift": 49.9481,
"LonDiv": 16988.76
}