I am opening Excel sessions in an automation. The way I do this is through the Microsoft Excel connector (open method).
In the next steps of my process my Excel macro tries to reconize the sheets that were just opened, with the Application.workbooks open method in VBA. The problem is that this VBA method doesn't work when the Excel sessions are opened this way. When I close the Pega Excel sessions and then manually open them, the Application.workbooks open method do works again.
Try setting the workbook property in the connector itself instead of passing the file name into it at runtime. Then instead of resetting the state, use open() and close() to activate the spreadsheet you need during runtime. ResetState() isn't listed in the documentation for the connector so I would be wary of using it.