I downloaded an Excel created by DataTables but when I open it I'm greeted with this ambiguous error:
I select Yes and the Excel opens with seemingly all of the data, but it's such a big spreadsheet that I can't tell if Excel recovered all data or not ("...as much as we can").
Does Excel tell you if it was unable to recover all data?
It doesn't tell you clearly, and yes, you might have 'hidden' loss.
I had that often in the last decades of working with Excel, and have stopped to ever use that function.
I recommend to read such messages as 'the file is corrupted, go find your last backup, or you will rue it later'.
Of course, if you don't have a backup, that is tough (it taught me to have backups). But continuing with a 'recovered' file, and finding months later that relevant data is missing, is often worse.
if the file is always generated that way, you don't have another option - take it and hope for the best. Aside from saving the result in a new file, and comparing the two with tools, there is no way to know if something was lost.
Note that *.xlsx is factually ZIP file - simply rename it to *.ZIP, and open it, and you can analyse all the pieces of the Excel sheet separately, in multiple sub-folder and (XML-)files. Maybe you can identify the problem point and fix it manually.
