When one of the labels/texts contains a special character, like < or > for example, the excel file you can download becomes corrupted.
That makes sense, since an xlsx file is basically an xml and the < and > characters are not allowed inside xml values or attributes.
I'm not sure there is an easy fix for this, but I wanted to report it in case anyone else encounters this.
Well, since you can use < and > just fine in Excel and Word, there's certainly a way to avoid it, so I'd consider this a bug.