No Font error on document profile

System

About a month ago, suspiciously soon after a Windows Update, our Worksite/Desksite suite began displaying a 'No Font' error every time a document profile was opened.
The fault was traced to a captioned canvas on the profile form informing users that marked fields are required.
Removing the canvas sorted the problem, but we would prefer the design to be as planned.
The same thing happens in all of the three libraries we use.
Has anyone seen this before?
If so have you identified the source of the issue.

Thanks