Same Issue
Three Scenarios with one File:
1) Opened locally on FMPA 13 with OSX10.9.2 => Interactive Container works as it should with pdf file
2) Hosted on FMSA 12 with Win2008r2
=> FMP12 & FMPA 12 Clients work as intended
=> FMPA13 Client displays Error Message that "File does not begin with '%PDF-'FM......pdf (see above error)
3) Hosted on FMS 13 with Win2008r2
=> FMPA 13 Client uploads fine, shows documents in design mode when show sample data is acitvated, in Browse Mode I get an "HTTP Status 404" Error Message - We tried this on 2 installations with all necessary Ports opened.
Whether the Container storage is internal or external open or secure storage does not matter ... we tried all possible combinations.
Additional: It seems that the Files located at the location .../Streaming/MainDB are named with UUIDs as filenames. This should not be a problem except for Windows claiming that the file names are either too long or invalid. We changed back and fourth between temp and permanent storage of thumbnails ... to no avail. I wonder if this would be the problem