Nintendo has sent out a message to Dragalia Lost players to let them know that an issue is currently affecting Shishimai’s demolishing reward. However, you can rest assured that the matter in question is being looked at and will be resolved as soon as a fix becomes available. The official statement regarding this from the development team is as follows:
We have confirmed an issue in the current In the New Year’s Tidings: Fortune from Afar event where the reward for demolishing Shishimai’s limb does not let a reward drop when it goes into Overdrive or Break resulting from the demolishing. This issue has been confirmed in all difficulties. We are currently investigating this issue. Any further updates regarding this issue will be added to this notice. Thank you for playing Dragalia Lost.