Why isn't the console waiting for the user to read the string?

Question

The essence of the program is this. You need to measure the response time to the server and write it to a variable. Everything works fine, but if I choose to have the list of available ip addresses read from a file, then the user needs to enter the path and filename. As soon as I start doing this, the compiler skips the lines

path = scr.nextLine(); 
filename = scr.nextLine();

That is, it looks like this, the user enters the number 2, and then immediately

System.out.println("Enter the path to the file"); 
System.out.println("Enter file name");

Even without giving the opportunity to enter the path and name, why is that?

public static void main(String[] args) throws Exception {
    int ipCount;
    byte choiceUser;
    ArrayList<String> ip = new ArrayList<>();
    ArrayList<String> averageTime = new ArrayList<>();
    HashMap<String,Integer> ipAndAverageTime = new HashMap<>();
    Scanner scr = new Scanner(System.in);
    System.out.println("1. Enter ip manually\n2. Read from file");
    choiceUser = scr.nextByte();
    if(choiceUser == 1) {
        System.out.println("Enter the desired number of ip addresses: ");
        ipCount = scr.nextInt();
        System.out.println("Enter " + ipCount + " ip addresses");
        for (int i = 0; i < ipCount; i++) {
            ip.add(scr.next());
            averageTime.add(getAverageTime(ip.get(i)));
            ipAndAverageTime.put(ip.get(i), (int) Double.parseDouble(averageTime.get(i)));
        }
        sortAverageTime(ipAndAverageTime);
        writeToFile(ipAndAverageTime);
        printResult();
    }
    else if (choiceUser == 2) {
        String path;
        String filename;
        System.out.println("Enter file path");
        path = scr.nextLine();
        System.out.println("Enter filename");
        filename = scr.nextLine();
        ip = readFromFile(path, filename);
        for (int i = 0; i < ip.size(); i++) {
            averageTime.add(getAverageTime(ip.get(i)));
            ipAndAverageTime.put(ip.get(i), (int) Double.parseDouble(averageTime.get(i)));
        }
        sortAverageTime(ipAndAverageTime);
        writeToFile(ipAndAverageTime);
        printResult();
    }
}