I am unfamiliar with the Cobra but from your description I assume that it’s an integrated amp with a DAC. My first suggestion would be to try to connect another digital input to the Cobra, such as a CD player or transport, or. cell phone with an appropriate digital cable, and see if that works. If so then you know that the issue is the digital interface with the CA and the Cobra.
Make sure you have the most recent updates on the amp and the streamer and your operating system on whatever device you are controlling them with (Android, Apple, etc). My CA CXN 100 was recently torpedoed by an Apple iOS update and the issue resolved when I updated the iPhone.
Check the CA Help tab on the Stream Magic app and ensure that your device is included in the list of compatible components. If it isn’t mentioned then email CA via the app. Also check all the settings on the Cobra.
Have you tried all the possible digital connections between the CA and the Cobra?