Frozen balances on Indodax can occur because there are still coin buy/sell transactions that have not been successful, usually because you use the limit order method when making transactions. When you place a coin buy or sell order and it has not been executed, the balance associated with the transaction will be frozen until the transaction is completed. To reactivate the frozen balance, you need to cancel the current order. Once the order is canceled, the previously frozen balance will automatically return to an active balance and can be used for other transactions or withdrawals. This process ensures that your funds are safe during the transaction process.