Create SimpleXMLIterator from XML submitted via HTML Form

I'm trying to accept xml that is submitted via a text area in an html form and create a SimpleXMLIterator object from it.

When the xml is submitted, it comes through I'm using the following to clean out the linebreaks and and decode the html entities:

$cleanedXml = stripslashes(html_entity_decode($xml));

But when I try to create my simpleXMLIterator from the result I get the error String could not be parsed as XML.

When I write the $cleanedXml variable to the error log the output look correct:

2015/01/03 22:16:32 [error] 2619#0: *907 FastCGI sent in stderr: "PHP message: <fmxmlsnippet type="FMObjectList">
    <Step enable="True" id="39" name="Sort Records">
        <NoInteract state="True"/>
        <Restore state="True"/>
        <SortList Maintain="True" value="True">
            <Sort type="Ascending">
                <PrimaryField>
                    <Field table="Company" id="1" name="ID"/>
                </PrimaryField>
            </Sort>
            <Sort type="Ascending">
                <PrimaryField>
                    <Field table="Company" id="2" name="Name"/>
                </PrimaryField>
                <SummaryField>
                    <Field table="Company" id="3" name="idSummart"/>
                </SummaryField>
                <OverrideLanguage language="English"/>
            </Sort>
        </SortList>
    </Step>
</fmxmlsnippet>';"

I can take the xml from that error_log output, write it into the $cleanedXml variable as a heredoc, and successfully create a SimpleXMLIterator from it:

$cleanedXml =  stripslashes( html_entity_decode($xml) );
error_log($cleanedXml); // grab the xml from the error log and heredoc-ed it in below:

$cleanedXml =<<<XML
    <fmxmlsnippet type="FMObjectList">
    <Step enable="True" id="39" name="Sort Records">
        <NoInteract state="True"/>
        <Restore state="True"/>
        <SortList Maintain="True" value="True">
            <Sort type="Ascending">
                <PrimaryField>
                    <Field table="Company" id="1" name="ID"/>
                </PrimaryField>
            </Sort>
            <Sort type="Ascending">
                <PrimaryField>
                    <Field table="Company" id="2" name="Name"/>
                </PrimaryField>
                <SummaryField>
                    <Field table="Company" id="3" name="idSummart"/>
                </SummaryField>
                <OverrideLanguage language="English"/>
            </Sort>
        </SortList>
    </Step>
    </fmxmlsnippet>
XML;

$iterator = new \SimpleXMLIterator($cleanedXml);
die(var_dump([$iterator])); // Object successfully created

Is there something I'm missing here? If I'm able to do it from the error_log output, why wouldn't I be able to it directly from the variable?