You have a cell array with the entries being numeric row vectors (not the column vectors you initialize.) The export routines will refuse to export that in one piece to a single csv file because csv files have no ability to store groups of numbers in one csv location. Each location in a csv must be either empty, or a numeric scalar, or a string (possibly double-quoted).
Perhaps you should loop writing one cell per file ? Or perhaps you should use an excel file and create different "sheets" ?