My guess would be more that he hasn't performed it enough to be really comfortable with singing it, rather than him having trouble singing it, it's well within his voice range and for once all the songs recorded for LH were done in a key he is perfectly able to sing.

I would further guess that it has been held back until another leg of the tour, probably Europe, maybe the stadium run next summer in the US so the sets are not all the same through out the tour.

As for him not liking it, Jon's personal favorites on any record are very often not the songs that fans like most, that is nothing new.