I am also seeing this problem.
Printer: HP OfficeJet Pro 8620 OS: Ubuntu 12.04.5 LTS 64 Bit LibreOffice: 3.5.7.2 Build ID: 350m1(Build:2) HPLIP: 3.12.2
The fix that Rob Cannell mentioned in Comment #6 seems to have solved the problem for me as well:
Under "File - Printer Settings - Properties - Device", change language from "PDF" to "Postscript (level from driver)".
I am also seeing this problem.
Printer: HP OfficeJet Pro 8620
OS: Ubuntu 12.04.5 LTS 64 Bit
LibreOffice: 3.5.7.2 Build ID: 350m1(Build:2)
HPLIP: 3.12.2
The fix that Rob Cannell mentioned in Comment #6 seems to have solved the problem for me as well:
Under "File - Printer Settings - Properties - Device", change language from "PDF" to "Postscript (level from driver)".