Workshare Desktop Add-In for Microsoft Office does not remain loaded in Outlook

Scenario

Install Workshare 9.0.0.6100 or later
Open MS Office
Click File >> Options >> Add-ins >> Manage: COM Add-ins >> GO
See Workshare Desktop Add-In for Microsoft Office is un-ticked
Tick this add-in and click OK
Go back into the Add-ins section and see that the add-in is still ticked
Close Outlook, re-open, go back into the Add-ins section
See that the Add-in is un-ticked

Resolution

There are many checks that can be made such as:
- Checking disabled items in Outlook
- Checking Registry load behaviour
- Running Outlook as Admin
- Check Workshare is licensed
- Disable other Outlook add-ins (to see if these have any effect)
- Run Workshare Configuration Assistant / Repair on Workshare
- Reinstall Workshare

In this case, the solution was to manually export the HKLM entry for the registry key Workshare.Desktop.OutlookAddin under
(HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Office\Outlook\Addins\Workshare.Desktop.OutlookAddin), and import to
HKEY_CURRENT_USER\Software\Microsoft\Office\Outlook\Addins\Workshare.Desktop.OutlookAddin

Steps

Click the Windows Start menu and either use the command box to type or just begin typing Regedit.exe
Press Enter
Browse to the location

HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Office\Outlook\Addins\Workshare.Desktop.OutlookAddin

Right-click this key and select Export
Save this file with an appropriate name to an appropriate location
Right-click the exported file, select Edit and change the registry path inside the file to read HKEY_CURRENT_USER\Software\Microsoft\Office\Outlook\Addins\Workshare.Desktop.OutlookAddin
Save and then run the file
This will import the add-in information into the Current User Reg hive as well as the Local Machine and resolve the issue

Workshare Desktop Add-In for Microsoft Office does not remain loaded in Outlook