The original basis of the show as I recall was that the ability of passengers to receive 'callings' resulted in danger to them from forces that would like to exploit this ability for nefarious reasons ("weaponize"!). But this is not a fair fight - our heroes do not have the resources to protect themselves from eeevil black ops govt whatever who could snatch them up at any time, especially Cal The Chosen One, if they wanted to and that would be that.
That the Major backed off and disappeared seems like evidence the writers realized this. Ben's continued justification to barge half-cocked into dangerous situations because 'protect family' notwithstanding. He is not in a position to protect jack shit.
But then if they are not in immediate peril, what 'standing' do they have to continue their investigation? What can they do that a blue-ribbon panel of the world's top physicists, with the help of cooperative passengers, could not do? Where is the blue-ribbon panel and why has Ben not got in touch with them? (There was such a panel wasn't there? Shown briefly on TV in like Ep 2.)
To procrastinate this conundrum of their own making, until cancellation saves them, writers meanwhile spin out endless tiresome variants of romantic folly. When they get stale throw in a couple more characters to romance about, because they can write pointless soap relationships for years. Include some chase scenes which together with the longing/angry triangles eat up episode time so they don't have to deal with the fundamental problem with the premise.
And make network happy by showing scenes of famileee working together, financial worries forgotten, doing google searches, preparing school projects, and galumphing around the house in big chunky shoes (looking at you Grace).
Introducing others affected by the same phenomenon, more or less, dilutes the concept still further because it means there was nothing unique about the flight, or the duration of their absence, or if there was anything special about the passengers themselves, other than just wrong place wrong time.
Secret govt program to weaponize electrical storms has surprising side effects of random time-jumping and giving varying degrees of poorly-understood clairvoyance to affected individuals. Govt follows up, affected persons organize and...well there is little they could do, really.
Am reminded of old George Clooney movie The Men who Stare at Goats for some reason, will have to take another look at that.