x_topbar_content shows up in the 'translate admin strings' page and 'Admin Strings to Translate', but is not available to translate in String Translations.
I would like to request temporary access (/wp-admin and FTP) to your site to take a better look at the issue. You will find the needed fields for this below the comment area when you log in to leave your next reply. Your next reply will be set to private.
Maybe I'll need to replicate your site locally to continue debugging and escalate if necessary. For this I’ll need to temporarily install a plugin called “Duplicator” on your site. This will allow me to create a copy of your site and your content. Once the problem is resolved I will delete the local site. Please confirm if this okay with you.
Our Debugging Procedures
I will be checking various settings in the backend to see if the issue can be resolved. Although I won't be making changes that affect the live site, it is still good practice to BACKUP the site before providing us access.