I realized yesterday a problem and it is reproducable from my side ... if I save a new Word Document over Boxcrypter with the filename "document1.docx" everything is fine. I can open it again and I can change it and it will be saved.
I can rename it now to "döcument1.docx" and I can still open it but Word can not save it back or Boxcrypter is saying upload failed.
I did not checked all special characters but at least with ö it does not work.
Is there a problem with ÄÖÜäöü in the filename ? I did not realized it before.