Some songs from forum playlists do not appear on main song list

[pdxdjazz]

I am not sure what you are experiencing.
When you download a list, it is added to playlists. Also each chart is checked by your app and if not an exact duplicate of an existing chart, it's added to your song library. If the title is a duplicate but the chart is different, the app appends a number to the new chart's title and adds it to your library.
Example:
You have a chart XYZ in your library.
You download a playlist with the identical chart. The playlist is added, your library is unchanged.
If you download another XYZ chart (in a list or not) that is not identical to your existing chart, it will be added to your library as XYZ 1. (and so on) your title numbers may be different from mine.

If your editor won't allow you to use a title that already exists, include an additional identifier code/initials/description in the title. Even a period (.) added to the title will make it different and the editor will allow it. eg. XYZ.

If your app is in fact behaving in a strange way, admin may have more questions to aid in troubleshooting the issue.
)BOB