The QAM channels seem to be jumping all over the place today.
Earlier today NBC moved to 12.1 (However I had a very weak signal and the channel kept pixelating). Sometime this evening that channel just disappeared.
CBS was also moved to 35.1 but has since returned to 99.2
Fox is currently on 66.1 and WQLN is on 54.1 (but this might also change)
I've rescanned my TV a couple of times tonight and still cannot locate NBC. Hope this helps.