Downloaded PDF files don't show description or "i" link to summary

I am including a PDF file in a podcast. The xml has both an <itunes:subtitle> section and an <itunes:summary> section for the PDF <item>.

Before the PDF file is downloaded in iTunes the subtitle shows in the description column and the summary is available via the "i" link on the right side of the description column.
After the PDF file is downloaded in iTunes both the subtitle/description text and the "i" link disappear.

There seems to be no way to access that information once the PDF is downloaded. The same issue does not affect audio or video files.

Does anyone know if this is by design (why?) or is it a bug in iTunes?