After a factory reset to the phone I noticed I couldn't access LTE any longer. I asked Ting and only offered a friendly suggestion that did not get back my LTE. So I researched and found that you must go into settings > Data Usage > Cellular Networks ( top right corner ) > Carrier settings > click on both 'PRL' and ' Update Settings' and update by clicking 'ok'. This ought to help get it back and if it does not, in combination of, I've also enabled all LTE bands and changed the settings on them each to assure all are at '1'.
If any of this has been tried or posted my apologies. Just want to put this out there while its fresh and to minimize user frustration. Good luck all!