Hello WPMU support.
I received the following tech support advice from Oxygen Builder support team.
My issue was Oxygen Builder was not saving in my newly spinned staging site, here on WPMU Hosting. Please see their response, and could you please advise a solution for sites hosted here and using Oxygen Builder?
Thank you kindly.
OXYGEN EMAIL:
The problem occurs because your server returns a 403 error when saving (https://d.pr/i/wWcBQU). A 403 error means “forbidden” and it occurs when the server/firewall prevents an action from taking place. You would need to work with your web host to find what action is being blocked so that they can whitelist it. If you send them login details for the site and a link to where they can see the 403 error, they should be able to inspect the site using their browser tools and check the Console tab for further information.
Additionally, when using WPMU, we’ve received feedback that some users need to add the following exceptions to the WAF firewall:
212340
211540
212800
211220
You’re hosting provider should be able to assist you with that if needed.
I hope this helps!