I’m getting the same problem,
I put an extra “in at the end of $urlString.'”, so now it reads
jQuery.get("' . ICSCALENDAR_URLPATH . 'ajax-load.php?showMonth="+jQuery(this).attr("month")+"'.$urlString.'"", function(data) {
Now I see that, in the function, the Quotes are being replaced with HTML entities.
”