Time and again i fall for this same simple mistake.
This may not be intuitive in the context of serialized arrays. If you fetch a serialized array with this method you want
$singleto betrueto actually get an unserialized array back. If you pass in false, or leave it out, you will have an array of one, and the value at index 0 will be the serialized string.
You see; if you have created a simple indexed array like $my_simple_array = array($someval); and stored it as custom field, you want to set single to true . Otherwise, the values you’d normally add like : $my_simple_array[]=$someotherval will be inserted as new arrays instead of string and you will end up with a mess like in the picture