[Ifeffit] Shift in Eo when fitting PtO2 and similar samples

Dear all, I am looking at EXAFS of PtO2 powders and Pt particles supported on TiO2. I used a beta-PtO2 crystal structure data for the PtO2 EXAFS and after the first shell fit, I observed a large shift in Eo (delta Eo of ~14 eV) in my fit parameters. When I tried to fit the Pt foil to obtain the So2, the energy shift also seemed high (delta Eo of ~7 eV). I am wondering if there could be a problem in the selection of Eo prior to EXAFS analysis? I left the Eo as the energy at the first peak of first derivative (ifeffit default). All of the data were also aligned using the reference foil in Athena before looking at EXAFS. I am wondering what would have caused this shift? Any help is appreciated, thank you. Best regards, Yanny