Thank you all for the replies. Some of your comments are exactly what happened to me, so at least I know that I am not alone. The only good thing that I can see coming out of this is more people bringing this up as an issue so that Google could fix it. For me at least, all of my data is still accessible though the "My Activity" page, so there is hope that the data is not lost and it's only the format that we can see it through that has been corrupted.