There could be many possible reasons for that.
- Many exchanges have various restrictions on API connections. You can see some of them here. For example. Delta will not import transactions for coins with 0 balances and 0 withdrawals and 0 deposits on Binance.
- It may occur because deposits and withdrawals are adding to or deducting from the balance even though they were just transfers. For example, if you only add Binance Connection to a portfolio and at some point you transferred 1 BTC from an exchange (for which you don't have an exchange account connection) or a wallet to Binance, the Binance Connection will import a 1 BTC deposit and add 1 BTC to your holdings. You may have already accounted for this 1 BTC as a buy transaction on the exchange. In this case you will need to manually edit the 1 BTC deposit entry and change the source of the BTC from
Other/UnknowntoExchangeorWalletso that it is treated as a 'Transfer' and not a deposit.