Yes, unfortunately this happens with all messages. (But I am able to access the properties "From, Subject, ReceivedDate," and they contain the correct values.)
In Scenario 1, when specifying EwsItemFields.TextBody, I get null values for both item.TextBody and Item.Body.
In Scenario 2, your recent suggestion was to replace EwsItemFields.TextBody with EwsItemFields.Body. When I do this, I get the following error:
Error: System.ArgumentException: Body field is not supported. (Parameter 'fields')
at Rebex.Net.Ews.GetMessageListAsync(EwsFolderId folderId, EwsItemFields fields, EwsListView listView, Object state)