For example, a free set of template animations by the author Zeggy, which can be downloaded from itch.io, Aseprite packs the sprite sheet incorrectly if you specify options:
Sheet Type: Packed
Trim Cels: True
Border Padding: 1
Spacing (Shape Padding): 1
In the picture below, I filled the entire area not used by the sprites with blue, and the places where the sprites are in contact with each other and with the borders of the atlas became visible.
Aseprite sometimes has bugs when packing the sprite sheete, related to spacings between the sprites and the edges of the atlas.
The Issue at Aseprite repository
For example, a free set of template animations by the author Zeggy, which can be downloaded from itch.io, Aseprite packs the sprite sheet incorrectly if you specify options:
In the picture below, I filled the entire area not used by the sprites with blue, and the places where the sprites are in contact with each other and with the borders of the atlas became visible.