Please see the "Troubleshooting Login/Connectivity Issues" at https://www.outlook-integration.com/docs/gettingstartedsuite/#troubleshooting_loginconnectivity_issues
We create parent-child relationship between the actionable emails and accounts. Although this is sufficient for the functionality that FrontEnd offers, it's not enough in order to view actionable emails as a sub-panel under accounts. For that we would need to create many-to-many relationship to accounts (and the same for contacts). We are planning to add this functionality to the next release that we are planning in few weeks. We'll let you know once it is released.
Can you please check if the server returning an error when you mark an email as actionable? Please check both FrontEnd log and the SuiteCRM server log. It sounds like either a relationship is missing or some permission issue.
