TV switches inputs on Marantz receiver when trying to use Chromecast with Nucleus

I have an LG OLED connected to a Marantz receiver via ARC HDMI. Chromecast is on another HDMI input on TV. Since nucleus has no video I’m trying to use Chromcast for that. Issue is TV changes receiver input to TV if Chromecast HDMI is chosen cutting off nucleus sound and changing input back to nucleus cuts off Chromecast. Any ideas on a work around?

Plug the chromecast into another HDMI input on the TV and then select it as the TV input. Play the nucleus to the AVR direct to an HDMI port. (doesn’t need to be ARC) Then use the chromecast as a display only ;see this link: Don’t use the chromecast as the roon “audio” endpoint.