We support all image tile layers as basemaps other than the default ones we provided in the current plug-in. You can find more basemaps from Living Atlas or ArcGIS Online and use this filter: type:"Map Service" AND typekeywords:"Tiled" to filter image tile layers. If there's data loading issues, you may check the viewstate logging for issues. One common reason is data projection. Please refer this doc page for more info.
I was using part of the base map service. Unreal engine will issue an error message='Invalid argument.' additional-message='tile info origin must have a spatial reference.
