No chapter marks in DVD made with FCP X

Hello!

I observe a very strange issue with Final Cut Pro X ...

Since a while I am re-arranging some of the surround albums I have on SACD, Blu-ray, DVD-Audio and DVD-Video as "fake" video DVDs to let my car audio system recognise and play them (since it only recognises proper DVD-Vs). This works like a charm, so far.

But now - all of a sudden - I have one project, which is rendered fine and also exports fine as a DVD image, but the chapter marks are entirely missing.

I have already tried deleting the whole project and recreating it, but that doesn't seem to do the trick.

Also, when just ommitting one specific surround audio track in that specific project, the DVD is exported just fine WITH chapter marks.

I can - however - not find any problems with that audio file.

It plays alright in Finder preview and FCP X and doesn't seem to be corrupted in any way.

Is there anything else, what I could check/change in connection with the missing chapter markers?

Does anybody know about some odd problems with FCP X and how to solve them in this context?

Please help!!

Many thanks in advance!