Thanks for reaching out. You may try to reboot or factory reset your TV. If the issue persists, I would suggest reaching out to Vizio support for additional help since the changes in the features and settings of the TV that has a built-in Chromecast are decided by the manufacturers. You may contact them here.
Thanks. I tried reaching out to them, and they claim it's a Google problem. I think I'm going to just buy a normal chromecast for my TV since I really enjoy the google photos ambient mode on the TV.
We understand that this is isolated with the ambient mode feature on your Vizio TV. Please note that we have very limited support on TV's with built-in Chromecast. If you're thinking of buying a separate Chromecast device, you may visit our Google Store. Let us know if you have other questions and concerns — we're here to help!
Due to inactivity, I'll go ahead and lock this thread after 24 hours. If you need help in the future, please feel free to start a new thread and we'll be happy to help.