Sprite disapears when moving left

Hi, I'm new to coding and followed some turotials on youtube.

Somehow my Sprite disappears when moving left. I also used character rigging (adding bones to the sprite).

WHen moving right, everything is fine, but the sprite disappears when moving left.

Here's the code:

using System.Collections; using System.Collections.Generic; using UnityEngine;

public class PlayerController : MonoBehaviour { //------------Variables---------------------------------------------------------

 private Rigidbody2D rb;     //Rigidbody of the player sprite
 public float speed;         //Moving speed
 public float jumpForce;     
 private float moveInput;    //A or D; left or right

 private bool isGrounded;    //Check if the sprite is attached to the ground
 public Transform feetPos;
 public float checkRadius;   //Checks the Radius between feetPos and the Ground

 private float jumpTimeCounter;      //Counts the times the player jumpes
 public float jumpTime;              //Checks the jumptime of the player
 private bool isJumping;             //Checks whether the player is jumping or not

 private bool facingRight = true;    //Checks whether the sprite is facing right
 //----------------------------------------------------------------------------------


 void Start()
 {
     rb = GetComponent<Rigidbody2D>();

 }

 void FixedUpdate()
 {
     moveInput = Input.GetAxisRaw("Horizontal");
     rb.velocity = new Vector2(moveInput * speed, rb.velocity.y);
 }

 void Update()
 {
     isGrounded = Physics2D.OverlapCircle(feetPos.position, checkRadius);    //Defining what means "isGrounded"

     if(moveInput < 0 && facingRight)    //calling the flip function: 
     {
         flip();                         //calls the flip function if sprite is moving left
     }

     else if (moveInput > 0 && !facingRight)
     {
         flip();
     }

     //-----------------------------------------------------------------------------
     //Make the player sprite flip sides (facing left and right):
     /*if(moveInput > 0)
     {
         transform.eulerAngles = new Vector3(0, 0, 0);   //Player facing right
     } 
     
     else if(moveInput < 0)
     {
         transform.eulerAngles = new Vector3(0, 180, 0); //Player facing left
     }*/
     //-----------------------------------------------------------------------------


     if(isGrounded == true && Input.GetKeyDown(KeyCode.Space))   //Jumping function
     {
         isJumping = true;                                       //Sets isJumping as true
         jumpTimeCounter = jumpTime;                             

         rb.velocity = Vector2.up * jumpForce;
     }

     if(Input.GetKey(KeyCode.Space) && isJumping == true)        //Jumping higher is key is pressed longer
     {
         if(jumpTimeCounter > 0)
         {
             rb.velocity = Vector2.up * jumpForce;
             jumpTimeCounter -= Time.deltaTime;      //So jumptimeCounter returns false at some point
         }
         
         else
         {
             isJumping = false;                      //Sets isJumping to false
         }

     }

     if (Input.GetKey(KeyCode.Space))                //Sets isJumping to false
     {
         isJumping = false;
     }

 }


 void flip()
 {
     facingRight = !facingRight;         //When the sprite is facing left
     transform.Rotate(0f, 180f, 0f);     //Turn the sprite at 180°
 }

}