Trouble finding others when in CQC on the Xbox One is most commonly down to NAT type restrictions on your network gateway/router.
Microsoft have created a handy Xbox One guide on how to improve your situation, you can find it here.
For help understanding what your NAT type is:
"A NAT (Network Address Translation or Network Address Translator) is the virtualization of Internet Protocol (IP) addresses. NAT helps improve security and decrease the number of IP addresses an organization needs." - searchenterprisewan.techtarget.com
If you are still encountering issues surrounding CQC matches, please contact our Support Team via the button below.