decrypting using tiny-AES-c

Question

I am using this c library, and have the following:

#include <stdio.h>
#include <string.h>
#include "aes.h"

int main(int argc, char *argv[]) {

  if (argc < 3) return 1;

  uint8_t *key = argv[1];

  uint8_t *content = argv[2];

  uint8_t iv[16] = { 0x0f, 0x0f, 0x0f, 0x0f, 0x0f, 0x0f, 0x0f, 0x0f, 0x0f, 0x0f, 0x0f, 0x0f, 0x0f, 0x0f,0x0f,0x0f};

  struct AES_ctx ctx;

  AES_init_ctx_iv(&ctx, key, iv);
  AES_CTR_xcrypt_buffer(&ctx, content, strlen(content));

  printf("%s", (char*) content);
  return 0;
}

it gives an output of random characters when used like this:

.\example key msg
prints <random chars>  

The problem is that the chars given are different each run (with same iv), if I try to decrypt the returned value from above, it won't return the original value

.\example key <random chars>  
prints more random chars

but if i use it like this:

#include <stdio.h>
#include <string.h>
#include "aes.h"

int main(int argc, char *argv[]) {

  if (argc < 3) return 1;

  uint8_t *key = argv[1];

  uint8_t *content = argv[2];

  uint8_t iv[16] = { 0x0f, 0x0f, 0x0f, 0x0f, 0x0f, 0x0f, 0x0f, 0x0f, 0x0f, 0x0f, 0x0f, 0x0f, 0x0f, 0x0f,0x0f,0x0f};

  struct AES_ctx ctx;

  AES_init_ctx_iv(&ctx, key, iv);
  AES_CTR_xcrypt_buffer(&ctx, content, strlen(content));

  printf("enc: %s\n", (char*) content);

  AES_init_ctx_iv(&ctx, key, iv);
  AES_CTR_xcrypt_buffer(&ctx, content, strlen(content));

  printf("dec: %s", (char*) content);
  return 0;
}

this encrypts and decrypts the value. it gives an output like this:

.\example key msg
enc: Vª≈  // encrypted (this changes every run)
dec: msg // decrypted

1. why does the encrypted value change each time for the same value+key+iv combination
2. why does the decryption work in the second example, and not when encrypting and decrypting separately