I am attempting to use the Noteability app with Dropbox which works well to synchronise the files (PDF). I mounted a BoxCrypter volume within Dropbox and have tried to use this folder within Noteability to sync my PDF files. The files work through the Noteability app, and continue to sync to the BoxCrypter folder, however I cannot open them from my Mountain Lion MacBook Pro in Adobe.
I have successfully moved PDFs in and out of the BoxCrypt drive from my MacBook directly so the issue seems to occur when the files is edited in the Notability app and resync'd back to the BoxCrypter folder.
I'm not sure what other information is useful other than the Notability app requires authorisation to Dropbox which I've reset up to test if something went wrong there but the problem still exists. I've also tried it in the BoxCrypt iOS app and it doesn't allow the file to be opened up there.
I'm going to post a similar issue with the Notability guys because they may provide some insight to what it's doing with the file which you guys may be able to use.