Hi,
I think that we have found source of your problem.
As I have noticed you are using ASPX templates. And the problem is related to your MasterPage template.
To generate metadata properly you should have literal control in your MasterPage <head> tag, for example:
<head runat="server">
<asp:literal runat="server" id="ltlTags" enableviewstate="false" />
</head>
And then simply in code-behind(your MasterPage .cs file) you should call method OnPreRender in which you will set its value to your page Header tags.
protected override void OnPreRender(EventArgs e)
{
base.OnPreRender(e);
this.ltlTags.Text = this.HeaderTags;
}
Please check if you have code like this in your MasterPage files , if not please insert it to your code and it should work correctly then.
Best Regards,
Zbysek Nemec