If Yoast freeze page backend editor please use this instruction. This problem is related to compatibility of Visual Composer with Yoast plugins and too long page to analyze. 


 


1. Please Go /wp-admin/ >> SEO >> Features


2. Disable Readability analysis



3. Scroll down and click Save Changes


4. If You use Yoast PRO version, please also disable "Cornerstone content" option: