I have exactly the same problem.In excell i cant see text characters. i attach an excell.
The problem caused after i upgrated feedback form 17(in moodle18) to feedback 19(in moodle182).
I restored the same survey(with the problem xls) in a pc with feedback17 (in moodle18) i exported a new xls, and it is ok.
And another question,how can i add page break in feedback19(i cant find it, in feedback17 it exists).
I would be very gratefull for any help.