If the metadata is missing, then it wasn't put there by ID. Please re-ask in the ID forum as Acrobat has nothing to do with the creation of the pdf.
Sure thing, thanks Michael.
Sounds like some type transparency flattening going on in there. InDesign itself has issues when exporting to lower PDF versions (1.3) and also if transparent objects are around say hyperlinks/buttons etc. The XMP data can be destroyed since it's been broken down and is not the original content any more.
Let us know if you explore in more detail in the ID forum, 2 doors down
thanks much ., ..it's on the indesign forum now. ..