When I export ProRes files it doesn't say H.264 in the "get info" section. It shows the Codec as "Apple Prores 422, Linear PCM, Timecode". It's a .mov file of course but I'm thinking that somehow you have something accidentally checked. In your settings, before you hit export, does it show ProRes HQ in your "summary: output"? I have no idea why you see H264 so I'm totally guessing here. When I export as prores, I basically select "Quicktime" as the Format, and then "Apple ProRes 422" (or 422 HQ) as the Preset and it should show as the codec in both the output summary and the video tab below. Good luck!