That's odd, Brian - I've also bought a 3-pack set, from one of the usual Amazon suppliers, and so far the first set is holding up nicely. They were no cheaper after postage, though.

The pack was the .012-.053 Phosphor Bronze Nanoweb type.

For my smaller 0 model guitar, I use the .011-.052 set - also Nanoweb, but just Bronze, not Phosphor Bronze.

The Tenor guitar takes the 2nd, 3rd, and 4th string from a standard .010 Phosphor Bronze Nanowen set - but I use any old .009 as a first, as the .010 top string from the set is on the edge of snapping if overtightened. (Tenor tuning is CGDA).

It's always possible that quality control varies, even with the best of firms. There was a period some years ago when the 3rd and 4th Elixirs from the .012 set were snapping very quickly. I and several other players formally complained to Elixir's European office - and they seemed to improve, but probably coincidentally!