I also have had this issue, as of today only.
Here is test html snippet which should work:
<html>
<head>
</head>
<body>
<a id="nabblelink" href="
http://rockeye-jms-tool-user.1059992.n5.nabble.com/">Test Rockeye Forum Embedded Script</a>
<script src="
http://rockeye-jms-tool-user.1059992.n5.nabble.com/embed/f4653544"></script>
</body>
</html>
regards,
Serge