I am having the problem with the ProBlog theme by Magazine3. Previously, I was having no issue with the plugin, so I assumed it was theme related. Although my themes author has spent hours trying to figure out the issue, and can’t find anything.
My webhost has also been trying to solve the problem, and found issues with it conflicting with W3 Total Cache, although it was running fine with it on previous themes. I switched to W3 Super Cache, and the problem persists.