To put it simply, knowing our oneness inevitably sets one free from suffering exactly as being set free from suffering implies that the individual must know our oneness. They go hand in hand.

Thus, if either one is missing the individual in question is simply deluding themselves. From what I've seen, they (either) suppress/ignore/bypass suffering while they still suffer, and/or they don't really know our oneness firsthand and only believe they do know it, all the while knowing only some description/interpretation/imagination of it.