JavaScript is acting suddenly unexpected

I have used successfully over long time the below JavaScript function in my theme options page.
It does save the WP Theme Options by JavaScript and puts a message on my screen once saved.

Suddenly, if I change the timeout settings (value) the message does either not show at all, or does show but does not hide anymore.

This is my JavaScript:

<!--Include AJAX save message + styles-->
<div id="saveResult"></div>
<script type="text/javascript">
  jQuery(document).ready(function() {
    jQuery('#myOptionsForm').submit(function() { 
      jQuery(this).ajaxSubmit({
        success: function(){
          jQuery('#saveResult').html("<div id='saveMessage'class='successModal'></div>");
          jQuery('#saveMessage').append("<p><?php echo htmlentities(__('Settings Saved Successfully','wp'),ENT_QUOTES); ?></p>").show();
        }, timeout: 5000
      }); 
      setTimeout("jQuery('#saveMessage').hide('slow');", 5000);
      return false; 
    });
  });
</script>

This is the according CSS:

.successModal {
  display: block;
  position: fixed;
  top: 35%;
  left: 20%;
  border-radius: 50% !important;;
  width: 123px;
  height: 153px;
  padding: 5px 20px;
  background-image: url("Smile-success.png");
  z-index:1002;
  overflow: auto;
  background-position: center center;
  background-repeat: no-repeat;
  -moz-border-radius: 15px; 
  -webkit-border-radius: 15px;
  -moz-box-shadow: 5px 5px 10px #cfcfcf;
  -webkit-box-shadow: 5px 5px 10px #cfcfcf;
}

This all worked very good until I uploaded the entire theme to GitHub, and then back down to my Computer.

Since then, not even a MAC Time Capsule Backup solves the problem.

The problem, if I change the timeout: 5000 to (which before was possible)
timeout: 2000 or any other value,
the message des not disappear any more and takes very long to show up.

Does any body have a idea what this could be?

I tried even a scratch version of options page.

What can be the issue for it stop work all of a sudden, even browser crossing?

I tried also MAMP Restar, fresh folders, fresh instal…

I really hope somebody can help me put here 🙂