I have this same problem, if it becomes helpful to have a second example.
Core Machine (Operating system/System info/Roon build number)
macOS 10.14.5, Roon 1.6(416)
Network Details (Including networking gear model/manufacturer and if on WiFi/Ethernet)
Orbi RBS50 (with Disable IGMP Proxying unchecked), 3*Orbi RBS40, Orbi RBW30.
Audio Devices (Specify what device you’re using and its connection type - USB/HDMI/etc.)
Auralic mini, Apple TV, Chromecast Audio, Chromecast Ultra 4k, Devialet Phantom