This is a new bug in 10.4 (BUG-000095459). We have Technical Article 000001060 talking about the relevant issues http://support.esri.com/technical-article/000001060
There are many interface properties which have input parameters (typically the parameters are indexes) that are affected in ArcObjects 10.4 Visual Studio 2015 VB.NET, like ITableSort, IFieldsEdit, etc. Workaround for VB.NET would be the same as suggested in Article 000001060.
This bug is fixed in 10.5.1 (check bug status: http://support.esri.com/bugs/nimbus/QlVHLTAwMDA5NTQ1OQ==).