Applies to customers on macOS 

First check that you have selected the same Primary Network Interface as the one also selected in Dante Controller.

RedNet Control > Preferences (⌘ ,) > Primary Network Interface. 
(In the example below the Primary Network interface is en6, yours might be another en number)

As of macOS Sequoia, Apple has added an extra security option for applications that use local networks. 
If you are on Sequoia and your Red/RedNet Devices are not appearing in RedNet Control but are appearing in Dante Controller please check that you have allowed Local Network Connection.

System Settings > Security & Privacy > Local Network > 
Check that RedNet Control 2 is enabled.