Importing Playlists from an external drive - now three years out of date?

Hi all, I have my music and media stored on an external drive. Apple Music and Apple TV on my current iMac (running macOS Sonoma 14.3.1) recognise all my playlists just fine, but I noticed the 'iTunes Library.itl' hasn't been modified since 2019. I have now just got a new Mac mini (also running 14.3.1). When I plug my external drive into the Mac mini and open the 'iTunes Library.itl' file on there, no music, films or playlist appear post 2019 - although they are physically all present on the external drive. The music, films and playlists show up again if I connect the external drive into my old iMac and open up Apple Music. What am I doing wrong?