Thanks for reaching out. Let's sort this out.
A few questions: What type of Chromecast device do you have? Does the white cross appear on your tablet or TV screen? What app are you using when you encounter this? Does this also appear when casting from a different Chromecast-enabled app? Please reboot your Chromecast and tablet. Reinstalling the app you're using may also help
We haven't heard back from FBX28826923, and it's been a few days, so I'm locking the thread. As always, feel free to make a new thread if you have any more questions or concerns.
Thank you for your help, Jennifer!