Chromecast Integration (beta) - Commands don't work (with Naim Mu-so 0870)

I have installed the Chromecast Integration (beta) app, and I am trying to add a new audio device which supports Chromecast.

I am able to discover the device, and the device is added into the device list. However, the status of the device doesn't update and none of the commands I send are working.

I have enabled debug logging and there are some error logs, I have googled them and searched the forum but haven't spotted anything useful yet.

Has anybody came accross the issue or can anyone suggest any troubleshooting steps please?

The device is a Naim Mu-so 0870

Some example logs are below:

[dev:45]2021-07-31 10:21:15.246 [error]org.codehaus.groovy.runtime.InvokerInvocationException: su.litvak.chromecast.api.v2.ChromeCastException: No application is running in ChromeCast (method runQ)

[dev:45]2021-07-31 10:20:30.677 [error]java.lang.NullPointerException: Cannot invoke method toInteger() on null object on line 307 (method volumeUp)