Script is only moving some of the records, despite console stating otherwise

I’m trying to simply copy text from one column to another. Only about 20% of the records are being copied over. However the console logs each name correctly…

Im using this script, which i’ve edited for my own use from here:

// set the table

let table = base.getTable("Inventory Item Summary");

// get the table records

let itemCode = await table.selectRecordsAsync();



// loop through the records

for (let record of itemCode.records) {

    // set variables to the record values

    let itemCode = record.getCellValue("Item Code");

    // only run on records which have notes

    if (itemCode) {

        output.text(`Copying notes for record ${record.name}`)

        // build the newNotes value from the notes...

        let newItemNumber = itemCode

        table.updateRecordAsync(record, {

            "Item Number": newItemNumber

        })        

    }

} 

Any help would be appreciated!

edit: i believe selectRecordsAsync() is deprecated, could this have something to do with it?

edit2: Doesn’t seem to be because of the deprecation, i changed it to:

let itemCode = await table.selectRecordsAsync({fields: ['Item Code']});

and still no change

edit 3:

Ive added an else statement, and it seems itemCode exists, and im not getting any ‘failed’ results

    if (itemCode) {

        output.text(`Copying notes for record ${record.name}`)

        table.updateRecordAsync(record, {

            "Item Number": itemCode

        })        

    } else {

        output.text('failed')

    }