Connecting to Excel downloaded from Reporting Services throws "External table not in expected format" error

Hi all,

I'm hoping to gain a deeper understanding of the issue as stated in the title. Here's the process flow:

1. Download report from ReportServer as Excel (xlsx)

2. Load the downloaded file on SSIS via ACE OleDB for further processing.

The error is thrown by the SSIS package. A rather common encounter, judging by the discussion on this thread https://stackoverflow.com/questions/1139390/excel-external-table-is-not-in-the-expected-format/51057571#51057571

I confirmed in the thread that the problem has a workaround by renaming the worksheet before feeding it into SSIS. However, upon further testing, I found out that renaming the worksheet isn't even necessary. All that is required is to:

1. Open up the workbook

2. Save (even without any changes)

And that allows the Excel file to be loaded without complaints! Can someone with the knowledge please share your insight on this matter? Thanks in advance!