Copy this file to a "normal" drive and try it again. If it not worked open and save the file with Excel and try it again. This is just to rule out issues with the sharepoint and/or an invalid file-structur.
Is the report being run by the same user in QV11 and QV12?
Or is one version on a desktop and one on a server?
If it is being run on a server reload, does the account running the QlikView Distribution Service have permissions to access the sharepoint folder and xlsx file?
1 - yes, I meant to try it from a real drive and not from a website like sharepoint which might lead to various issues which aren't related to Qlik.
2 - no, just opening and saving the file with a desktop Excel without any change within it or to the fileformat. Files created by an online Excel or any third party tools could be different to an origin Excel file.