The cryptocurrency ShadowCash uses traceable ring signature to anonymize the sender of a transaction. However, these were originally implemented incorrectly, resulting in a partial de-anonymization of ShadowCash from their first implementation until February 2016 by Monero Research Labs researcher, Shen Noether. wiki
From the technical perspective, how was Shadowcash's implementation of ring signatures fixed which prevented the partial de-anonymization of it? What was the fix and by whom was it performed?