So from what I gather, Fannie Mae's website indicates you are eligible for HARP, however then the lender runs it through DU (Fannies underwriting system) it does not indicate you are eligible?
There are two HARP products - DU Refi Plus and Refi Plus. DU Refi plus allows you to refinance your mortgage with any bank that offers the program. It requires an "Eligible" determination through DU, no exceptions.
Refi Plus is the manually underwritten version of the program, but it is ONLY able to be offered by the company that currently services your loan.
So I would check with your current lender to see if they offer the Refi Plus (not DU Refi Plus). If not, then you will have to wait until Fannie Mae can update your information so you can do the DU Refi Plus with the lender of your choice.
Please be aware that your loan being owned by Fannie Mae and getting the mortgage prior to 2009 are not the only criteria for being eligible for HARP, so the DU findings you are getting may be accurate or they may be in error.
Refer to the following link for more information: https://www.fanniemae.com/content/faq/harp-du-refi-plus-faqs.pdf
Hope this helps!