Is it possible that your attributes do not have `default` attributes set up, such that `show tau` with no additional attributes would show nothing at all? That's an issue with the crop tool, as it only uses the provided image tag (e.g. `tau`) for cropping purposes. Your layered images should always have sensible `default` attributes set if they're required (e.g. a default mouth attribute because the character should always have a mouth). It looks to me in the screenshot like if you don't have a `tbase` attribute set, the sprite simply doesn't have a base at all and is made up of the hair/arms/expression parts, which supports this. You can set up attributes with the `default` keyword e.g.
group tbase auto: attribute casual default