@Terence
Problem has been resolved on your site.
Root of problem is not with Blog plugin, but with some else, that is adding osclass version of TinyMCE into every page of oc-admin and that cause conficts.
This can be easily fixed by adding following code to start of index.php of plugin.
$act = Params::getParam('action');
$fil = Params::getParam('file');
if($act == 'renderplugin' && @explode('/', $fil)[0] == 'blog') {
osc_remove_script('tiny_mce');
}