Hi guys;
I’m the Autoptimize maitainer and happened to read this (wp-org matcher for the win). I’ve been able to trace this problem down to Autoptimize not handling the presence of a Byte Order Marks in the CSS-file very well.
Download Converter Member; if you open up wp-content/plugins/autoptimize/classes/autoptimizeStyles.php and around line 105 change
//<link>
if($css !== false && file_exists($css) && is_readable($css))
{
$css = $this->fixurls($css,file_get_contents($css));
}else{
into
//<link>
if($css !== false && file_exists($css) && is_readable($css))
{
$css = $this->fixurls($css,file_get_contents($css));
$css = preg_replace('/\x{EF}\x{BB}\x{BF}/','',$css);
}else{
(so adding that preg_replace-line, basically) then the BOM-character will get janked from the aggregated CSS-file and all will be well. I’ll make sure this is in the upcoming 1.7.0 as well.
hope this helps,
frank