I am a little unclear on your most recent response, though. Thank you for attaching your new sample with the new Excel workbook.

Please let me know if you have any other questions or concerns on this matter. Would it be possible for you to please verify the behavior you are seeing with your 'sample breakage.xlsx' so I may continue looking into this issue to find out if it is a bug in the Excel engine or whether this is actually expected behavior? When you try opening the 'sample breakage.xlsx' file on your machine, does it open in protected view? If so, then the workbook that is created by loading your file via the Infragistics Excel Engine will load in as 'protected' and therefore will export as protected as well. I believe that this is likely expected behavior, but I believe I need a little bit of information from you on this matter first. After setting it to not be in protected view, which essentially then 'trusts' the file, I am not seeing the 'opens_in_protected_view.xls' file opening in protected view when creating it with the sample project you sent. After reading up on Protected View in Excel, I found that Excel files that originate from the Internet may open in protected view, so I tried opening the 'sample breakage.xlsx' file that you have attached in Excel 2013 and found that it was originally in protected view. I have been looking into this a bit, and I was initially able to reproduce this issue you are seeing.

Excel open in protected view