steps to reproduce:
add new config "Sample Configuration Nested"
go to "Sub Config 2 List" and add an item and save
go to "Sub Config List"
expected: path should be displayed as "... / item1 / jcr:content / Sub Config List"
but is displayed as (separator missing): "... / item1jcr:content / Sub Config List"
you should test this with AEM 6.3 and deploy using the script clean_install_deploy_package_aem63.sh of the wcm.io caconfig sample app.