I made some purchases from walmart.com when mrrebates/aa shopping mall had dropped their rate to 1%/1 point.

At the time bigcrumbs showed 2.4%. Both purchases posted, but they posted with 0.8% cashback.

They said they will contact walmart but haven't heard anything back. I'm also not so sure this is walmart's problem, seems like they were late updating their site to the new rate walmart is paying but they should honor it. It's quite a bit of $$ difference too.