elites are usually oblivious to the lack of buy-in from the lower levels of society. This has become increasingly a problem as the voting franchise has been ever more widely extended throughout the 20th Century.

The voting franchise has been effectively declining for decades. In the US, the extreme case, only about 50% of potential electors bother to vote, and this tendency is steadily rising in Europe. However, I wouldn't ascribe this to lack of buy-in to elite moral values, but to economic factors, and simple pragmatism : why bother, when there is no electoral offer which corresponds to my interests? Government of the middle class, by the middle class, for the middle class (in the best case!)

Sure, there is a plurality of the population, and of electors, who don't buy into progressive moral issues, and may feel that their voice is not being heard, and may seize on big-ticket events like Brexit or a US presidential election to express their rejection of ... well, pretty much anything and everything. There is not much we can do about them, except wait for them to die, and invest in social engineering so that their children will be better people.

Oh, and improve the economy so that it works for them. Then, they will generally no longer feel impelled to stick up their middle finger on the "moral" issues.

_{It is rightly acknowledged that people of faith have no monopoly of virtue - Queen Elizabeth II}