Hi there,
Tabs are working with no problem in the new version, this must be a conflict of some kind which needs to be investigated.
Please move your website to a staging server and update the theme and the Cornerstone to the latest version.
Then please follow the steps below:
- If you’re using a CDN, please clear the CDN’s cache and disable optimization services.
- Test for a plugin conflict. You can do this by deactivating all third-party plugins, and see if the problem remains. If it’s fixed, you’ll know a plugin caused the problem, and you can narrow down which one by reactivating them one at a time.
- Remove custom CSS and Javascript from the options or Child Theme and test the case.
- Increase the PHP Memory Limit of your server. Click here for more detailed information and how to increase the PHP memory limit.
If you still experience the problem kindly get back to us with the result of the steps above and URL/User/Pass of your WordPress dashboard using the Secure Note functionality of the post to follow up the case.
Thank you.