Why the time function doesn’t work properly

Question

I’ve met a problem with time function in C.

This program is a game which I just learned from a book, and its part function is: Showing user some numbers for 1 second, then hide them. But when I run this program, the numbers Never display, just be hidden directly. I put the relevant block out then the program runs properly without time function, but I can’t find the problem, I don’t know where is wrong in this block.

Here is code:

#include <ctype.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
int main(void) {

  const unsigned int delay = 1;
  char play_again = 'Y';
  int number = 0;        // user's input;
  int tries = 0;         // attempt
  int digits = 0;        // number of digits in sequence
  time_t seed = 0;       // seed value for random number sequence
  time_t wait_start = 0; // stores current time
  bool correct = true;
  int score = 0;
  int total_digits = 0;
  int game_time = 0;
  clock_t start_time = 0;

  printf("\nWelcome to this game, i think you know"
         " the rules,so press enter to play:"
         "remember, number only display %us!",
         delay);
  scanf("%c", &play_again);

  do {
    // initialize game

    correct = true;
    tries = 0;
    digits = 2;
    start_time = clock();

    // inner loop for game
    while (correct) {
      ++tries; // a new attempt
      wait_start = clock();

      // generate a sequence of digits and display them
      srand(time(&seed));
      for (int i = 1; i <= digits; ++i)
        printf("%d ", rand() % 10); // output a random digit

      /*this block has a problem but I can’t find it neither I understand
        it...*/
      {
        // wait one second
        for (; clock() - wait_start < delay * CLOCKS_PER_SEC;)
          ;

        // overwrite the digit sequence
        printf("\r");
        for (int i = 1; i <= digits; i++)
          printf("  ");
        if (tries == 1)
          printf("\nEnter the sequence\n");
        else
          printf("\r");
      }

      // input sequence and check it against the original
      srand(seed); // reinitialize sequence
      for (int i = 1; i <= digits; i++) {
        scanf("%d", &number);
        getchar();
        if (number != rand() % 10) {
          correct = false;
          break;
        }
      }

      // on every third successful try, increase length
      if (correct && ((tries % 3) == 0))
        ++digits;

      printf("%s\n", correct ? "Correct!" : "Wrong!");
    }

    // output the score when game finished
    score = 10 * (digits - ((tries % 3) == 1));
    total_digits = digits * (((tries % 3) == 0) ? 3 : tries % 3);
    if (digits > 2)
      total_digits += 3 * ((digits - 1) * (digits - 2) / 2 - 1);
    game_time = (clock() - start_time) / CLOCKS_PER_SEC - tries * delay;
    if (total_digits > game_time)
      score += 10 * (game_time - total_digits);
    printf("\n\nGame time was %ds,"
           " Your score is %d\n",
           game_time, score);
    fflush(stdin);

    // check if user required new game
    printf("\nDo you want to play again?(y/n):");
    scanf("%c", &play_again);
  } while (tolower(play_again) == 'y');

  return 0;
}