The data can be be fixed by following the below steps
1. Ensure a full backup of the PR / Process Repository has been recently created
2. Open the Adminutil.exe (\\TIBCO Nimbus\Client)
3. Browse to the PR / Process Repository location
4. Login as an administration
5. Go to Tables > Other Tables > Attachments Table > Fix Duplicate ID's
6. Take note of the result. A detailed log can be found within \\PR\System\Logs\Diagnostics\FixDupAttGUIDs.log
7. Close the adminutil.exe and try to publish the storyboard
If you still have the same problem, of if you have any questions or concerns about these steps please contact TIBCO Nimbus Support by raising an SR to https://support.tibco.com