For decades this mystery prompted quantum physicists to admonish their peers and students to just "keep your head down and calculate".

Quibble. They tried to devise ways to prove (or, better, disprove) it. They have since been able to demonstrate it repeatably. They have also been able to counter Bell's opposition (Bell's Theorem, as I recall) by using a truly random astronomical event to trigger the EPR experiment, which then demonstrated quantum entanglement. I think I even posted that on this board a year or three ago.

We still don't know how it happens. But the math works, and it describes the reality we observe.

I'm not going to buy Zurek's book. I did some searching, and he does have a proper paper.

https://journals.aps.org/rmp/abstract/10.1103/RevM...

At first glance, this doesn't quite sound like the Quanta author. Or maybe he tried to simplify too much. We already know that the quantum reduces to the classical on the macroscopic (and non-relativistic) scale. He seems to be describing how. BTW, he only mentions "entanglement" once in the entire paper, and not in the context of the original article.