Here's a solution that identifies what elements of the cell array contains data and then moves those elements to a matrix initialized with zeros.
This assumes ui_table_data was taken from your UI table ( hObject.Data ).
hasData = ~cellfun(@isempty, ui_table_data);
uiTableData = zeros(size(ui_table_data));
uiTableData(hasData) = [ui_table_data{hasData}];
