We are currently evaluating this issue and will update this article when we have more information.

Alternate workaround
When an incoming email is added as an Action to NXT, it adds only the action itself.  If a specific Fundraiser needs to be assigned to that action, the Action record must be opened and the Fundraiser (Solicitor) added to the Action. 

The user must open the Action and click Assign To: "Me" link and save the action record or search for another Fundraiser(s) and save the Action once selected.