Infinite SEO Error

Show "all posts"in the admin dashboard is only showing the last post and this is the error showing under "title tag" which is blocking all other posts and entries

"Fatal error: Call to undefined function won_hb_convert_tri() in /home/xxxx/public_html/xxxx/wp-content/plugins/wpmu-dev-seo/wds-files/wds-core/wds-core.php on line 222"

This has been there since the last two updates and I would have though should have been addressed by now but for some reason it seems unreported?