Our MS Dynamics account uses the Team as the contact owner instead of a User. Based on our business model, that's needed because more than one person might need to access an account/contact. We realized that since updating to the newer managed solution our email send activities are no longer logging on the activity timeline. After working through some troubleshooting with your support, we discovered it worked after changing the owner to a User from the Team. (Support also saw in the error that system user ID could not be found.) Is there a reason why the integration can't look for either a Team or User ID since Team is an out of the box option with Dynamics?