The fact that the "new name" (IEI) seems to ignore/discredit the primary claims of the sufferers at the outset, and that a multi-billion (trillion?) dollar industry would somewhat prefer these people don't exist, I remain skeptical of recent studies. (A view no doubt also biased by personal experience.)
That older studies show the effect, and newer ones don't isn't a smoking gun, but it is a cause for skepticism.
At least, one thing almost all studies agree on is "more research is required".