Hi, we need more details to help you, like in the doctor office:

1. Template Name / Developer ?
2. PHP version ?
3. With what addon you had problems, all or selected?
4. Do you have this same problem on all pages?
5. Can you edit this same page using admin (back-end) editor?

Hi,

• I use a lot of templates and it happens with every single one of them: rhino, wimble, barber,...
• i use on some sites 7.2, 7.3,7. 4
• Not particular addon
• Have this problem on all pages
• I can edit an addon, click save, and then edit it again en whoops everything gone I recorded this and it happened twice... Using chrome https://file.io/PlyjT2wFGZhT

Hmm, werid indeed. Very rare issue. Can you also use different browser in case of....

AND Can you share access to website where we can see this error. URL + Super User. Use "Hidden Content" field. Tomorrow I will be able to check & talk with our developer.