Thanks for reaching out. Please try to remove then re add the TV under remote and accessories in the GTV settings. Also, try to plug the Chromecast device on a different HDMI port on your TV and try to set up your Voice Remote by following the steps listed in this support website article.
Just checking in to make sure that you've seen my response. Please let me know if you have other questions or concerns as I will be locking this in 24 hours if I won't hear back from you again. Feel free to start a new thread and we'll be happy to help.