In Outlook 2016:
If I select a message and then go to file/print in the main outlook 2016 window, I get "OpenPGP Encrypted message
Please wait while the message is being decrypted / verified..." This does not change and it does not decrypt the message.
If I double click the e-mail message so it open in a new window, and then hit file/print in the newly opened window it works just fine.
Small annoyance to be sure.