Process substitution doesn't work with diff and node

I'm trying to compare the output of my fizzbuzz.js program: for (let i = 1; i <= 100; i++) { let out = ""; if (i % 3 == 0) out += "Fizz"; if (i % 5 == 0) out += "Buzz"; if (i % 3 && i % 5) out = i; console.log(out); } with the contents of a expected-output.txt file which contains: 1 2 Fizz 4 Buzz Fizz 7 8 Fizz Buzz 11 Fizz 13 14 [...] I can't get process substitution to work: diff -u expected-output.txt <(node fizzbuzz.js) seems to hang indefinitely. What could be causing this? My environment is macOS Mojave, bash 3.2.57, node v12.5.0. EDIT: this seems to be a macOS issue. Everything works fine on a Ubuntu 18.04 machine with newer bash 4.4.19