LinkedIn recently made some changes to the way they handle security on their API meaning that some links to LinkedIn from the Dashboard are no longer compatible. We have released a fix for this issue, but a few users are still being affected. 

If you are still experiencing issues with posting to your LinkedIn page please follow the below steps:

1. Go to Add/Edit services. 
2. Click the 'Edit' button opposite that service. 
3. Select the reconnect option as shown in the below image. 
4. Follow the steps to re-link the account.
5. Click "Update Account" so the new settings will be saved.