I just came across that this morning while reviewing my online User Guide. Under Identifying Print Media Sources and Specifications, there is an asterisk that says "Duplexer support user-specified print media that are 149 mm to 220 mm wide and 210 mm to 355.6 mm long." 149 m = about 6", 220 mm = about 7-3/4", 210 mm = about 7-1/4" and 355.6 mm = about 14".

 

So a 5.5" sheet is a half inch too narrow for the duplexer to pick up. It also won't work to feed it wide, because it needs to be 7.25" minimum for the duplexer to work.

 

A possible solution is to print two-up and trim, if the paper isn't pre-cut. Lastly, you can work-and-turn, the old fashioned way.

 

I was disappointed, too.