Edit: I got it working by instantiating my AVURLAsset with the AVURLAssetPreferPreciseDurationAndTimingKey option: let asset = AVURLAsset(url: audioAsset.fileURL, options: [AVURLAssetPreferPreciseDurationAndTimingKey: true])

This breaks on Sep 1 2022 for some reason: po formatter.string(from: 30 * 24 * 3600) // returns "0 months"