I know that JumpCloud has many good support articles on support.jumpcloud.com (Search LDAP) showing syntax for LDAP queries. The one thing that I see is that there is no port specified on the Path, for example ldap.jumpcloud.com:636.
2 articles that will show up in the search are Using JumpCloud's LDAP as a Service and Creating LDAP Groups.
If those articles are not helpful, feel free to continue to work with the JumpCloud Support Team for more help. It looks like you have an open case with them.