One of my most celebrated recent "null result" was published in Biological Psychiatry, a journal with an impact Factor about 13 last I checked. Even though it was a null result, it was decently powered longitudinal study that provided evidence inconsistent with the prevailing view in autism research. Even if there exists a difference that we failed to detect, it probably much smaller than what others had expected on the basis of second-grade evidence (cross-sectional group differences).