I wanted to reply to this thread, but it has been closed for comment:
I had the same issue and found that the Cloudflare WAF was interfering with the Divi update of the Home page. Divi techies escalated it to their higher support team. They found they were being blocked by Cloudflare.
I deactivated Cloudflare WAF and the page update issue was fixed.
Please would someone from Cloudflare comment on this? Specifically, what settings of the WAF could be interfering with the Divi Wordpress Theme? What granularity is needed to make the WAF work with Divi?