Epic Games acknowledged the issue, said to be affecting a "small percentage" of players. As of today, however the company still hasn't found a solution, outside of blaming high demand.
"We've had millions of successful matches played online so far," senior producer Rod Fergusson explained. "However a small percentage of players , which is unacceptable. We're working closely with Microsoft to address the matchmaking issues. I promise you that it is our #1 priority, and we hope to have an update soon."
In the interim, Epic recommends trying a different playlist, playing with more than four friends in private matches, which seems to limit the problem, and ensuring you're router is properly configured to "open" NAT.
"I apologize for any issues you may be having and I hope the above workarounds give you a better experience until we are able to correct the issue," Fergusson added.