Thank you for using the Support Forum. Please make sure you are loading the envelops correctly. Try printing from tray one. You can find the loading instructions for the bypass and the tray one in this article from the online support for your printer. Also try printing your envelope to a regular sheet of paper and see where on the paper the envelope information is printing this will help you to determine how you need to load the envelopes.
If this does not help please consider contacting your support centre for further assistance.