Ben, since the issue is on your site only and can not be reproduced on default Oxwall installation or our demo, most likely it was caused by one of the following:
1. Incorrect update. Make sure that ow_utilities/html_tag.php and ow_libraries/jevix/jevix.class.php files on your site are the same as the ones from the default Oxwall package.
2. If they are the same, then one of the third party plugins might be causing this ( most likely plugins related to SEO).