I'm using Debian 10, whenever I try to import a playlist it does nothing. I get to choose the folder, select the files, but then nothing is imported.

So I was wondering, where the playlists are saved? Can I manually import them?

If you are using the gtk3 version it's because there is a bug from the porting to gtk3, I've fixed it in git. Thanks for reporting it.

The playlist are not saved in independent files.
To be honest I don't use m3u lists myself so the support for them is rather minimal. Generally, lists are discouraged unless you care about the order of the songs, using labels is a much more flexible solution in most cases. That doesn't mean I won't improve the use of lists, but there is so many other things that I want to improve...

Thank you for your reply!

I use them not because I care for the exact order, but because I have over 4k songs, many many albums, back in windows I used musicbee to make playlists for each occasion. The thing is: 80% of my music files have some wrong labels... because musicbee auto-tag kind of made a mess with them (like there are songs labeled 3 different genres and none of them is the right one), so is not really a problem of your software! (actually, after trying on at least 10 other linux music players, this one won my heart, even after Clementine)

I like this concept of preferring labels over playlists, seems better now that I'm thinking about it. The migration from the different organization methods is the only annoying part of it.