Here is my google app script. The aim of the script is to look for duplicate values in column C and then highlight any duplicate value rows that it finds.

If i run the script from the editor window it runs just fine and highlights those duplicate rows but if i run it from a trigger either by form submit or time driven then the array returns undefined and so all rows are highlighted.

function findAndHighlightDupesInColumn() {
      var col=col||0;
      var ss=SpreadsheetApp.getActive();
      var sh=ss.getActiveSheet();
      var rg=sh.getRange("C2:C10");
      var vA=rg.getValues();
      console.log(vA)
      var uA=[];
      for(var i=1;i<vA.length;i++) {
        if(uA.indexOf(vA[i][col])==-1) {
          uA.push(vA[i][col]);
          console.log(uA)
        }else{
          sh.getRange(i+1,1,1,sh.getLastColumn()).setBackground('crimson');
        
        }
        
      }
      
    }

Here is the output of the console.log when run inside the editor window.

8:00:32 AM  Info    [ [ 1071184 ],
  [ 1069157 ],
  [ 1069567 ],
  [ 1098033 ],
  [ 1068959 ],
  [ 1090405 ],
  [ 1097753 ],
  [ '' ],
  [ '' ] ]


8:00:32 AM  Info    [ 1069157 ]
8:00:32 AM  Info    [ 1069157, 1069567 ]
8:00:32 AM  Info    [ 1069157, 1069567, 1098033 ]
8:00:32 AM  Info    [ 1069157, 1069567, 1098033, 1068959 ]
8:00:32 AM  Info    [ 1069157, 1069567, 1098033, 1068959, 1090405 ]
8:00:32 AM  Info    [ 1069157, 1069567, 1098033, 1068959, 1090405, 1097753 ]
8:00:32 AM  Info    [ 1069157, 1069567, 1098033, 1068959, 1090405, 1097753, '' ]

Here is the result when i run it from a time based or form submit trigger.

Dec 17, 2021, 7:38:38 AM    Debug   [ [ 'Job ID' ],
  [ 1071184 ],
  [ 1069157 ],
  [ 1069567 ],
  [ 1098033 ],
  [ 1068959 ],
  [ 1090405 ],
  [ 1097753 ],
  [ '' ],
  [ '' ] ]


Dec 17, 2021, 7:38:38 AM    Debug   [ undefined ]

Can anyone help? I have been banging my head against a wall with this issue.

Thanks!