I would recommend checking out the articles below to make sure you have the default tray set correctly:
I press the menu and choose Admin Settings, then Printer Settings. I can scroll to Bypass Mode and choose "on". I can then scroll to the paper mismatch settings and choose label or envelope. The print job goes off well. The envelope prints from the bypass tray. HOWEVER, when I try to go back to Tray 1 as my default tray printing 8.5" X 11" paper, scrolling to Bypass Mode and choosing "off" does not result in the printer automatically printing 8.5" X 11" from Tray 1. Why not? . I try to set every setting for Tray 1 to be for 8.5" X 11" paper. Sometimes my fiddling works. Sometimes it does not and I have to turn the printer off and on again. I would like to use Tray 1 for 8.5" X 11" and the Bypass Tray for non-8.5" X 11" paper and be able to configure the Bypass Tray to accomodate whatever type of paper I am using there. .