New Mac's library does not appear on ATV under "Computers"

Long-time ATV user and I usually have one or two Mac libraries that I access through the ATV. In the past, when I got a new Mac it was quite straightforward to set it up so that I can see the library on the ATV. I got a new Mac Mini on Black Friday and I set it up as I usually do. I can AirPlay movies from the Mini library to the ATV, but the Mini library does not appear as a source in the ATV "Computers" menu. I checked that Media Sharing is enabled. Rebooted both the ATV and Mini. Ensured both are on the same network. Any advice? Thank you.