Camera won't rotate while holding WASD keys

Hi,

I've coded up a simple, generic, first person controller. The WASD/arrow key controls and the mouse rotation for the camera work fine individually, and the arrow key controls work fine in conjunction with the mouse controls as well.

However, the mouse controls won't work (the camera won't turn/rotate) while holding the WASD keys. The player will still move in the direction that I'm holding, but the camera won't turn until I let go of the keys. I'd greatly appreciate any help getting the WASD keys to play nice with the mouse as that would be the ideal movement for the game. Here's my code:

 using System;
 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class Movement : MonoBehaviour
 {
     Animator animator;
 
     public bool canMove;
     public Transform cam;
     public float sensitivity = 100f;
     public CharacterController controller;
     public float speed = 12;
     float xRotation;
     private float desiredX;
 
     public Transform groundCheck;
 
     void Start()
     {
         animator = this.gameObject.GetComponent<Animator>();
         Cursor.lockState = CursorLockMode.Locked;
         canMove = true;
     }
 
     // Update is called once per frame
     void FixedUpdate()
     {
         //inputs
         float mouseX = Input.GetAxis("Mouse X") * sensitivity * Time.fixedDeltaTime;
         float mouseY = Input.GetAxis("Mouse Y") * sensitivity * Time.fixedDeltaTime;
         float x = Input.GetAxis("Horizontal");
         float z = Input.GetAxis("Vertical");
 
         //controls movement
         if (canMove)
         {
             Vector3 move = transform.right * x + transform.forward * z;
 
             controller.Move(move * speed * Time.fixedDeltaTime);
             
             //camera look
             Vector3 rotation = cam.transform.localRotation.eulerAngles;
             desiredX = rotation.y + mouseX;
 
             xRotation -= mouseY;
             xRotation = Mathf.Clamp(xRotation, -90f, 90f);
             cam.transform.localRotation = Quaternion.Euler(xRotation, desiredX, 0);
             transform.localRotation = Quaternion.Euler(0, desiredX, 0);
 
             //controls animation
             animator.SetFloat("InputY", z);
             animator.SetFloat("InputX", x);
         }
         else
         {
             animator.SetFloat("InputY", 0);
             animator.SetFloat("InputX", 0);
         }
     }
 }