idvd issues- iTunes link missing from audio import. trying to upload playlist. will only let me upload one song

What system are you using? Where is you library located?

I have the same problem with 10.11.5. Didn't try it with the earlier 10.11.4 system.

The only workaround I've found is to drag your iTunes folder into iDVD's Media/Audio pane. You can access the tracks there by artist.

That's about the best we can do as iDVD is on its death bed.

Have you found this to be true?

Yes. We only have access to the actual audio files, not the iTunes database that contains the playlists.

However, you can select multiple tracks in the Media pane when holding down the Command key and drag them to the add music box:

I've found that the tracks will play in the order you chose them.

There are a number of video DVD authoring apps available from the App Store. None have the versatility of iDVD but some do have a couple of basic themes. Many are free or have a demo version.

I've only tried a few to see what features they offered but have no other info on them. We've been spoiled by iDVD and it's hard to accept anything less.