Can I ask if this happens on all kind of browsers, after you use only Toolset and Theme Twenty Seventeen on your site?
==> Backup your site before you disable Theme and Plugins, or do this on a staging site.
We had a similar issue in the past where if you clicked very fast, twice on a save button, the JSON was parsed as you see it now.
I could however not replicate this with the currently stable versions and Toolset only.
Well - thanks for sharing the file but the download link you shared is not working.
Can I check first on your site - could you please share wp-admin access details with problem URL where I can see the issue.
*** Please make a FULL BACKUP of your database and website.***
I would also eventually need to request temporary access (WP-Admin and FTP) to your site. Preferably to a test site where the problem has been replicated if possible in order to be of better help and check if some configurations might need to be changed.
I would additionally need your permission to de- and re-activate Plugins and the Theme, and to change configurations on the site. This is also a reason the backup is really important. If you agree to this, please use the form fields I have enabled below to provide temporary access details (wp-admin and FTP).
I have set the next reply to private which means only you and I have access to it.
This ticket is now closed. If you're a WPML client and need related help, please open a new support ticket.