I can reproduce. Works with Adobe, but not with *PDFDebugger* nor with *Decrypt* command line options.
I have a feeling the document is using an unsupported form of encryption, but it will likely require debugging the source to find out. Probably worthy of a bug report: https://issues.apache.org/jira/projects/PDFBOX/issues/PDFBOX-4690?filter=allopenissues -Tres - tres.finocchi...@gmail.com
