Envelopes printing upside down on M608

We recently replaced one of our older HP models with an M608. This model has a reversed (upside down) paper orientation compared to our original model. No worries, we found the printer setting to change to reverse that. And now it works great for everything except envelopes printer from Linux. Envelopes printed from Windows works fine. Envelopes printed from Unix to other printer models work fine. But when Linux sends a print job to this machine, the envelope prints upside down.

Is there a specific way we need to print to this device to make it recognize the correct orientation for an envelope? Or is there a printer setting that would help? I've tried sending print jobs with the following lp options, none of which work: mediatype=envelope, HPOption_envfeeder=true, pagesize=env10, mediasize=env10, media=env10.

I can manually rotate the print job (orientation-requested=6) and that will get it to print properly. But that's not a terribly good solution.