FlexBlock "Saving Issues" error
In the majority of cases, this issue is due to the fact that there are not enough resources to proceed with an X amount of information. In order to solve this, it is needed to erase the revisions with the help of the WP-Optimize plugin.
Important note: erase only the revisions!
WordPress revisions automatically record any changes you make to pages or posts on your website. A new copy of a page is created every 60 seconds by default, as well as every time you click on the Save Draft, Publish, or Update buttons Another reason is the restrictions that are imposed on the server side, in most of the cases a 403 error can be seen inside the browser’s console. In such cases, it is best to contact the hosting provider and ask them to investigate the issue and solve the restrictions conflict.