This may be a plugin or theme conflict. Please attempt to disable all plugins, and use one of the default (Twenty*) themes. If the problem goes away, enable them one by one to identify the source of your troubles.
If you can install plugins, install “Health Check”: https://wordpress.org/plugins/health-check/ On the troubleshooting tab, you can click the button to disable all plugins and change the theme for you, while you’re still logged in, without affecting normal visitors to your site.
Also this plugin tell you if issue with the Rest API.
Still trying to figure this one out.
Used HealthCheck but it returns more information than my brain can absorb.
Also, when I got out of HealthCheck all my plugins were still deactivated, had to go back in and manually activate each one.
Saving keeps switching between Saving and Autosaving.
Updating grays out, then switches back to Update before immediately graying out while showing Updating.
This YouTube video shows what is happening, seems particularly bad on longer pages.
But, the page doesn’t update.
However if I do Ctrl / F5 and refresh it indicates there is a new autosave version. If I choose this version it usually has the updated.