Yes, Me too! I accidentally deleted a playlist in Rekordbox (6.6.1).
I spent a week creating and curating it. Then I created a new folder and dragged my new playlist into it. After that, I deleted the 'spare copy' of the playlist in Rekordbox. I opened the Playlist in the new folder and it was empty, no tunes. Why is there not a 'Deletion History' where you can select and 'Restore to Playlists'?
I've spent an evening online, on the Pioneer website (useless), Rekordbox forums, the wider web and have attempted the varied and disparate 'solutions'. Now I'm getting worried. I would like to get my work back.