MX-Q App Not Finding XR18 Console, But X-Air App Works Fine – Why?

I'm using a Behringer XR18 mixer connected to a wireless router. The setup works perfectly with the X-Air app on my devices, but when I try to use the MX-Q app to control a monitor bus, it fails to find the console. The app just keeps scanning but never finds the console. Has anyone experienced this issue or found a fix?