Thank you for your post.
Which browser are you using to access the hosted file in Web Direct? Make sure you are using FileMaker Server 13.0v4 to host the database file on Mac OS X 10.10 (Yosemite).
Access the hosted file using FileMaker Pro 13.0v3, create a new table with one Container field, format the Container field for Interactive Content, add one record and insert (not as a reference) any of the FileMaker Pro PDF files, and commit the record. Once you verify the PDF file displays properly, try accessing the file again using Web Direct and verify the PDF file displays properly. If so, then remove the Container field from the original layout, and add a new instance of the Container field.
Keep me updated with any progress.
I used Safari, Chrome and Firefox. I was accessing via a Filemaker hosting service so I assume they were using the latest FMP server. I recall the server hosting tech saying something to the effect that there could be security protocols that they can't relax for interactive files. [?]
Thank you for the additional information.
Make sure the hosting service has the necessary ports open. For a listing of ports that need to be open with FileMaker Server 13, see Knowledge Base Article #12120: