Maybe Elixirs are going through a bad patch. Years ago I bought 5 sets of Martin lights on a special offer, and I hated them. The ball ends tended to pull off when changing, and after about two hours they went through a 'dead' period, and never really came bright again. I've never bought any since, but reading this thread makes me think that those problems are past.
The one set of Elixirs that I've used were lovely to play, but too bright for my guitar and taste.