PHP PDO is saving string from javascript object (ajax) as empty field

PHP PDO is saving string from javascript object (ajax) as empty field

This is interesting and by that I mean incredibly frustrating.
I am passing this data to my php file via an ajax call: {"html":"<div>I'm
a div!!</div>"}
I want to preface this next statement by saying that I do understand the
reasons for not saving json to a database, but it does have a use here.
When I save this data to the database field, the field is empty. Now see
this:
$in1 = file_get_contents('php://input'); //from ajax
var_dump($in1);
$in2 = '{"html":"<div>I\'m a div!!</div>"}';
var_dump($in2);
value of my ajax call:
string(33) "{"html":"<div>I'm a div!!</div>"}"
string(33) "{"html":"<div>I'm a div!!</div>"}"
Perfectly the same! Yet, $in2 will save to the database just fine!! While
$in1 yields an empty field!!
To be certain, consider this:
if ($in1 === $in2) { echo "They're equal!"; }
Go figure...they're exactly equal, yet one will save correctly and the
other won't. Amazing.
$params = [':item' => 2, ':in'=>$in2];
$query = "UPDATE plugin_instances SET config=:in WHERE id=:item";