@Epsi Try this again online; here’s why she’s Once-per-Chain, Bing-translated from Japanese:
■ (2): If this card uses “Maldolche Puddingcess” as the X material, when the “Madolce” card from your graveyard returns to the deck, you can remove one of the X material of this card and activate it. The monster effect of special summoning one “Madolce” monster from the deck with a front attack display or a back defensive display is an inducing effect. (It is not an effect that takes the target.) When activating this effect, you will remove one of the Exies material on this card as a cost. This effect can be activated multiple times in one turn, but not multiple times on the same chain. Also, it cannot be activated in the damage step.