Thanks for reaching out and for being a step ahead of us — we appreciate it! To cover all the bases, could you tell us what type of Chromecast device do you have? What mobile phone are you using to connect it to the network? Is this an initial set up or working previously? In the meantime, please reboot your Chromecast, Wi-Fi router, and mobile device. Also, reinstall the Google Home app.
Let me know how it goes.