hashid encryption returning no value in PHP

Question

Was trying to encrypt text:- "Michael Fehr" or "carpet" using hashids, it returns blank.

Code:-

$hashids = new Hashids\Hashids("mysalt");
$hashed_text = $hashids->encode_hex(bin2hex("Michael Fehr"));

echo "<script>alert('".$hashed_text."')</script>";

Also tried:- $hashed_interestrate = $hashids->encode_hex("63706b64");, but not working. If I try text:- "CPC", it's working.