Apple Music on my Android phone is suddenly not showing the Cast icon.

Apple Music on my Android phone is suddenly not showing the Cast icon.

I have used the phone for years to successfully cast to my Chromecast Audio.

Here's the solutions I've tried.

1. Numerous times of re-starting the phone.
2. Numerous times of uninstalling and re-installing the app.
3. Re-starting the Chromecast Audio
4. Changing the password on my Apple account and checking the sign out of all devices. (This did not result in the Music app being signed out. So I re-installed it - which forced a new sign in.)
5. I have checked my Wi-Fi settings and both the phone and the Chromecast Audio are connected to my home Wi-Fi.

The only anomaly that I am aware of is that I used a Chinese android phone for a day and signed into Apple Music on that phone. (I do not have access to that phone now. It has been factory re-set. When I check iTunes it still shows as a connected device.)

Help to get this fixed would be much appreciated.