PHP - Get JSON body from HTTPS request

I have some PHP files that access some JSON in the request body and then acts on it.

I get the JSON using:

$json = file_get_contents('php://input');
$input = json_decode($json, TRUE);

And access the values using:

$input["val"]

However, I just upgraded to HTTPS and have deduced that is not reading/receiving any JSON.

How do you get JSON data out of a HTTPS request?

from PHP - Get JSON body from HTTPS request