Board Thread:General Discussion/@comment-4310945-20131229044249/@comment-11051098-20140104015346

It might simply be that when Aizen caused the Hollowfication of the Visored, the Hôgyoku was still at a state unable to grant them a Resurreccion. Or he simply wanted them to Hollowfy to die from soul suicide, while with Tôsen, he wanted him to achieve a Resurrección.