Go's `fmt.Println()` overprints previous lines read from a file with `bufio` `Scanner`

Question

This is a small snippet of code supposed to read a list of space-separated values of first name and last name from a text file and put the result into a slice in Go. For some reason, only the first item is stored in the slice:

package main

import (
    "fmt"
    "bufio"
    "os"
    //"io"
    //"strings"
)

type Person struct {
    fName string
    lName string
}

func main() {

    // a scanner to read input with spaces
    scanner := bufio.NewScanner(os.Stdin)

    fmt.Print("Enter a file name: ")
    scanner.Scan() 
    fileName := scanner.Text()

    scanner = nil //close this scanner
    
    file, err := os.Open(fileName)
    if err != nil {
        fmt.Fprintf(os.Stderr, "os.Open error: %v\n", err)
        return
    }

    fmt.Println() //empty string

    fileScanner := bufio.NewScanner(file)
    fileScanner.Split(bufio.ScanLines)

    var persons []Person = make([]Person, 0, 3)

    for fileScanner.Scan() {
        line := fileScanner.Text()
        fmt.Println(line)

        var (
            firstName string
            lastName string
        )
        
        fmt.Sscanln(line, &firstName, &lastName)
        
        person := Person{truncateString(firstName, 20), truncateString(lastName, 20)}

        persons = append(persons, person)
    }
  
    file.Close()

    fmt.Println("Items: ", len(persons))

    for i, element := range persons {
        fmt.Printf("%v %s %s\n", i, element.fName, element.lName)
    }

}


func truncateString(input string, length int) string {
    if len(input) > length {
        return string(input[0:length])
    } else {
        return input
    }
}

To debug it I added an fmt.Println() to print out the lines of the input file. Surprisingly, it does not print the strings on new lines, but rather, as far as I can judge from the output, it overwrites the strings over the same line.

For the input file:

Harper Collins

Billy Bons

John Bon Jovi

It gives the output:

Enter a file name: names.txt

John Bon Jovis

1

0 Harper Collins

The last s is obviously from a longer name overwritten.

What can be the reason?