php spreadsheet excel reader returning anonymous values

I am using php spreadsheet excel reader to read a excel file and do some manipulation. It was working fine and suddenly started to return value 'General' in case of integer columns

Sample rows from excel:

Code:

$dataFields = array("alias"=>"alias","store_quantity"=>"store_quantity","godown_quantity"=>"godown_quantity","name"=>"name");

$mandatoryFeilds = array("alias","store_quantity","godown_quantity","name");

$fieldsPos = array();
$data = new Spreadsheet_Excel_Reader();
$data->setOutputEncoding('CP1251');
$data->read($_FILES['upload-file']['tmp_name']);
for ($j = 1; $j <= $data->sheets[0]['numCols']; $j++)
{    
     if ( isset($data->sheets[0]['cells'][1][$j]) == true )
     {
          $fieldsPos[$data->sheets[0]['cells'][1][$j]] = $j;
          if(array_search($data->sheets[0]['cells'][1][$j],$mandatoryFeilds)!==false)
          {
               unset($mandatoryFeilds[array_search($data->sheets[0]['cells'][1][$j],$mandatoryFeilds)]);

          }
     }
}

if(count($mandatoryFeilds)>0)
{
     die('Some of the mandatory columns are missing in excel');
}

for ($i = 2; $i <= $data->sheets[0]['numRows']; $i++) 
{
    //printing the output here to check values received from excel which are some anonymous values getting returned
    var_dump($data->sheets[0]['cells'][$i]);

}

Output:

array("alias"=>"General","name"=>"Item A","store_quantity"=>"General","godown_quantity"=>"General")

Can anyone help me on this? Any help will be seriously appreciated

The issue happened because i updated my OS from Ubuntu 14 to Ubuntu 16 which updated the Libre Office version from 4.2 to 5

The excel file in Libre 5 is getting read in above discussed manner. So it has to do with Libre version rather than anything from Spreadsheet reader.