Aperture RAW processing too dark?

I recently imported a set of pictures of my daughter into my Aperture library. Everything went smoothly and looked great with the previews looking like I expected. I even went through each picture one by one and flagged the ones I wanted to edit. After editing a few I went back again and looked at the unedited pictures to see if there were any more i wanted to flag and edit. Upon doing this, I noticed that after Aperture finished "Loading..." a couple pictures, they automatically got significantly darker. A couple of them to the point that adjusting "Exposure" to the highest setting makes it barely acceptable for use. On one picture I noticed got even darker after the 2nd "Loading..." process.

As a test I exported the originals to my desktop, loaded them in Lightroom, and voila, the pictures are back to their "non-dark" selves. Therefore, I believe this is an Aperture issue and I have no idea why re-"Loading..." the RAW originals would make an image even darker. I've attempted to reprocess the originals but it pops up that none of the images need reprocessing.

Any suggestions?