The assigned liquidator for the collapsed New Zealand-based cryptocurrency exchange Cryptopia says it's making progress in determining customer holdings, but that the management of user funds by the exchange has caused delays.

Professional services firm Grant Thornton New Zealand was assigned to oversee the liquidation process in May, after the exchange had failed to recover from a major hack in mid-January.

In its latest update on Wednesday, Grant Thornton provided some good news, saying that it had managed to retrieve Cryptopia data that was stored in a third-party data center in Arizona. The liquidator previously filed for bankruptcy protection in the U.S. in order to protect that data, as the Arizona firm was in dispute with Cryptopia and was seeking $2 million in compensation.

Grant Thornton also provided an insight into the way the exchange had been managed, listing two primary reasons it has taken so long to find out which and what amount of cryptocurrency customers held with Cryptopia.

Firstly, the firm says, customers were not assigned individual wallets. Instead, "the crypto-assets themselves were pooled (co-mingled) in coin wallets. As a centralised exchange, users' trades would occur in the exchange's internal ledger without confirmation on the blockchain."

As such, Grant Thornton says it's not possible to determine individual ownership using the keys in users' wallets. Cryptopia did keep records of customer holdings and "reported these on the exchange," however.

The second reason for the delay is that Cryptopia never reconciled its customer databases with the cryptocurrencies actually held in its wallets, according to the liquidator. As such it must undertake the mammoth task of manually comparing the database with the wallets to ascertain customers' holdings.

Grant Thornton said:

The update added that, as a precaution, Grant Thornton it's continuing to move the remaining crypto assets held by Cryptopia into a secure environment, as it's still not clear how the exchange was hacked.

It's also still working with the New Zealand Police and "other authorities internationally" to pinpoint the source of the January hack and retrieve the funds.

The New Zealand Courts must yet direct the return of Cryptopia's crypto assets to its former users, Grant Thornton said.

Cryptopia image via Shutterstock