What version of MB are you using? (Help > About)
How was MB installed? (Store, Installer, Portable)
What steps are you taking to export the playlist?
What playlist format are you exporting to?
Does this happen with all playlists or just a specific one?
If specific, does it happen every time you try to export it?
MusicBee v3.5.8109.36974D, Win11, Installer.
Selecting random tracks in library, right click, add to playlist, external playlist. The same happens if i choose to export any playlist within the playlist tree-view.
As you can see, I can't choose the format, there is no option, but i believe it's m3u.