Sound off should be at the very start of the line near 1650. The reason the sound does not align with your text is because you used @pause for a beat.
Knock Knock @pause for a beat
Your issue is with the narrator line 1646. Try to write knock knock without the caps. The script is mistaking it for a character. You can also try to add a period at the end of knock knock to see if that’ll work as well.