Playlists disappear

Playlists disappear periodically. More precisely, the names of the lists themselves are. But when you click on any one, it turns out to be empty. You have to search the library again for the desired file and add it. How do I save the entire playlist as a single file? The entire library? And how do I add new files to the playlist? I search through the search bar and then add. Is there another way?

Usually the playlists are saved with your Audirvana database…
you can see the path where it is in the preferences of Audirvana…

backup often that file .sqlite

You add a playlist with + sign…
you name hit and hit enter.
You can after right click it to change it or export to desktop when it is all set for a backup…

you can add song in it by just dragging them over…
you can select many in one time and drag them over also