TL;DR:
Using MacBook Pro with Spanish - ISO Keyboard.
Solution: Ctrl + -
Full story
This is an old post but reading it got me thinking about possible shortcuts.
My keyboard is a Latin Apple MacBook Pro, which is called Spanish - ISO. I tried the changing keyboard distribution to U.S. solution... this works but with this solution I have to switch keyboards every time I want to comment which... sucks.
So I tried ctrl + - and it works. The - is where the / is located in an english keyboard but doing Cmd + - only changes the Chrome's zoom so I tried Ctrl which isn't as used as Cmd in macOS.
My takeaway with this would be: if I have more shortcut problems I might try the original shortcut but using the key where the U.S. keyboard would have it.