Why can't I detect a subject/background on Lightroom or Lightroom Classic?

I’m trying to detect the background/subject while editing pictures, but I keep getting the message “no background detected. couldn’t find background to select” on all images. This is a recent issue that I’ve been having and can’t figure out why. I’ve updated my Mac and Photoshop software, reset my computer, and made sure my GPU settings were set to auto. How do I fix this?