Home Sharing shows Music media but not Photos media

Hi, my Apple TV isn't showing any of the video media in my Photos library on my Mac Mini. Here are my details:

Mac Mini running Ventura 13.4 (M2)

AppleTV 4K running tvOS 16.6

Both devices restarted, re-signed into same AppleID, and both toggled the 'Home Sharing' switch using same AppleID

Both devices have wifi disabled and are on the same network via ethernet

I have a different Mac Mini on my network but it has Home Sharing disabled.

When I launch 'Computers' on my AppleTV, I don't even see a list of computers. I see an empty Movies library but I see a Music library that appears to have all the playlists and manually imported music in my Mac Mini's Music library.

Using my iPhone, it has the same issue as the AppleTV, so I'm thinking it's a problem with my Mac Mini. Actually oh my phone, I see a "Showing only content on Jeffery Chow's Library" so I think it's seeing the library, just not any of the content in it.

Can anyone think of what might be the issue pls?

EDIT: It occurs to me that my Photos Library isn't set to be my System Photo Library, because it's on an external drive and I'm backing it up with Time Machine. Could that be the issue?