Macbook doesn't see Chromecast

Hi melb_sammy,

Restarting will refresh macOS and the connections, which can often correct issues, so if you haven't done so yet, restart your computers. Updates often include fixes and can help with overall performance. If there are any updates available, install them to see if that helps: Update macOS on Mac. It's a good idea to create a backup before installing any available updates.

"Use Software Update

Before following these steps, it's a good idea to back up your Mac.

1. From the Apple menu  in the corner of your screen, choose System Settings or System Preferences.

• If you chose System Settings, click General on the left side of the window. Then click Software Update on the right.
• If you chose System Preferences, click Software Update in the window.

1. Software Update then checks for new software. 

• If Software Update finds new software, click the button to install it. The button might be named Update Now, Upgrade Now, Install Now, or Restart Now, for example. You might then be asked to enter your administrator password.
• If Software Update says that your Mac is up to date, then no new software is currently available for your Mac model. Software Update shows only software that is compatible with your Mac."

If you need additional help, Chomecast Help may be able to assist further: Chromecast Help.

Regards.