Doesn't anything she wears or touches go invisible too? I honestly don't know if that was this invisible girl or one of the other non-Fantastic Four invisible girl characters that exist.
As the Invisible Woman, Susan can render herself wholly or partially invisible at will by bending light around her.[50] She can also render other people or objects fully or partially invisible too, affecting up to 40,000 cubic feet (1,100 m³) of volume.
EDIT:
Invisible Girl
Initially, her powers are limited to making herself invisible. However, before long Sue discovers she can make other things invisible as well as create force fields of invisible energy.