Edit 1/12/2024: I mean, the playlist can be redone, but why is it emptied after a reboot?
In my tests, I have seen the list been emptied when connection to Internet (Tidal) was lost. May be this explains the trashing of all pieces in that smart playlist.
Thanks for reaching out with your report. Losing your internet connection may have had something to do with the issue, are you able to reproduce the behavior at-will? Can you let us know the local time + date of when you noticed the issue last time and when you notice the issue occur again?