I cannot give you a definitive reason. General consensus is that it is due to the tube model having less RAM. I am not aware of specific info from Plex or Nvidia.
Still, the issue exists. Search the forum and read the posts.
One other note: You must connect the Shield to your AVR, not to the TV. 2020 & newer LG TVs block dts audio formats over HDMI-eARC. See Audio Passthrough section of testing performed by rtings.com (linked below).
