PyGame Unsupported Image Format (but only sometimes)

I have a few files, following a video tutorial on how to make a platformer in PyGame. I keep getting the error pygame.error: Unsupported image format, but this only happens every now and then. Probably 5% of the time, the image files will load as the player, and the other 95% of the time, if I recreate the directory a few times, it might work.

This is the full error message:

Traceback (most recent call last):  File "/Users/Serena/PycharmProjects/GApp/code/main.py", line 73, in <module>    game.run()  File "/Users/Serena/PycharmProjects/GApp/code/main.py", line 54, in run    self.overworld.run()  File "/Users/Serena/PycharmProjects/GApp/code/overworld.py", line 118, in run    self.input()  File "/Users/Serena/PycharmProjects/GApp/code/overworld.py", line 97, in input    self.create_level(self.current_level)  File "/Users/Serena/PycharmProjects/GApp/code/main.py", line 32, in create_level    self.level = Level(current_level,screen,self.create_overworld,self.change_health)                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^  File "/Users/Serena/PycharmProjects/GApp/code/level.py", line 28, in __init__    self.player_setup(player_layout,change_health)  File "/Users/Serena/PycharmProjects/GApp/code/level.py", line 165, in player_setup    sprite = Player((x,y),self.display_surface,self.create_jump_particles,change_health)             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^  File "/Users/Serena/PycharmProjects/GApp/code/player.py", line 8, in __init__    self.import_character_assets()  File "/Users/Serena/PycharmProjects/GApp/code/player.py", line 47, in import_character_assets    self.animations[animation] = import_folder(full_path)                                 ^^^^^^^^^^^^^^^^^^^^^^^^  File "/Users/Serena/PycharmProjects/GApp/code/support.py", line 13, in import_folder    image_surf = pygame.image.load(full_path).convert_alpha()                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^pygame.error: Unsupported image format

Here is the code for the import_folder() function and the import_character_assets() function.

def import_folder(path):    surface_list = []    for _, __, image_files in walk(path):        for image in image_files:            full_path = path +'/'+ image            image_surf = pygame.image.load(full_path).convert_alpha()            surface_list.append(image_surf)    return surface_list

    def import_character_assets(self):        character_path = '/Users/Serena/PycharmProjects/GApp/graphics/character/'        self.animations = {'idle':[],'run':[],'jump':[],'fall':[]}        for animation in self.animations.keys():            full_path = character_path + animation            self.animations[animation] = import_folder(full_path)

However, it loads one image (not animated) in the overworld.py file using this function:

class Icon(pygame.sprite.Sprite):    def __init__(self,pos):        super().__init__()        self.pos = pos        self.image = pygame.image.load('/Users/Serena/PycharmProjects/GApp/graphics/character/idle/1.png').convert_alpha()        self.rect = self.image.get_rect(center = pos)

Also, the image files are all 64x64, and are in the correct directory. I've tried using the absolute file path, relative path, and path.join(), but it doesn't seem to make a difference. Any ideas? Thank you in advance!