The Canada Post shipping tool for the Canadian Library Materials Service administered by CULC/CBUC
This issue has now been resolved.
Over the weekend (February 12) Canada Post updated the software that the Library Shipping Tool uses. It has come to our attention that many libraries are no longer able to print their labels. Canada Post is looking into the issue.
Update: It has been identified as a problem across all users of the software. A trouble ticket was logged with their IT department and we are waiting for the problem to be fixed.