Are you placing the container field from a related table inside a portal? Interactive container fields do not work as interactive when placed inside a portal.
Thank you for your post.
The information from PhilModJunk is correct (Thank you). PDF files in Interactive Container fields cannot display in a Portal. This can be found in FileMaker Help -> Designing and creating databases -> Editing objects, layout parts, and the layout background -> Formatting and setting up field objects in Layout mode -> Specifying formats for container fields. Scroll to the bottom and read the section under "Notes".