Automation script updating duration always results in 0:00 value

I am passing a duration type field a number value for update:

let [audioFile, duration] = await concatenateFiles(audioUrls);
console.log(duration); // this is showing a number with decimal
// make the update
await table.updateRecordAsync(record, {
    AudioURL: audioFile,
    Duration: duration,
    Status: {name: "Done"}
});

All 3 fields are updated but the duration is always zero after this update. Do I need to supply something other than a number to the duration data type?

Edit: I tried to use Math.round(duration) to no effect