HollaEx like other popular and standard exchanges uses a smart address and wallet management system. All the generated addresses assigned to the users are valid on the blockchain network.
Due to the blockchain network constraints, exchange's internal transactions can not be handled and transactions can be unnecessarily expensive. Therefore HollaEx manages deposits and withdrawals of the users’ wallets intelligently and internally.
This means that the Bitcoin wallet address assigned to each user is for the purpose of depositing crypto from addresses outside of the HollaEx platform to the HollaEx wallets and when the users want to withdraw from their wallets, it is the exchange responsibility to manage and update the users' balances, in this case, blockchain does not necessarily represent your HollaEx wallet balance and that is why sometimes the balance shown on the blockchain may be less, more or sometimes equal to what the user sees in the HollaEx wallet.