When this happens the formula component in the Smart Workpapers Add-in has disappeared. To check, go to Excel, then File>Options>Add-ins
Note: The Add-in should contain both the HowNow Smart Workpapers (COM) and the HowNow Smart Workpapers Formulas (Excel) components for the workpapers to calculate correctly.
There are two options for resolving this issue:
Option 1 - Logout of the Smart Workpapers website, close Excel and then re-login to the Smart Workpapers website and open Excel.
Option 2 - Reinstall the Smart Workpapers Add-in, found here.