Further testing today, I don’t know if it helps but I found out there is no problem with search on Plexamp. It works flawlessly and manage to find titles even with articles in no time.
Weird because my music library is, by very far, my biggest library. And Plexamp has no problem to dig in it. Only regular Plex clients are concerned by this in my case.
For example, If I am looking for “Born to Be Alive”. I need to write “born alive” to get a result on Plex but I can write it correctly on Plexamp.
My server is on Docker (Unraid) Version 1.32.7.7621