There could be many possible reasons for that. Here are some reasons and how to fix them:
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.
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.
PRO TIP: Ensure that the connection was fully synced and all transactions were imported. To learn how to manually sync a connection, follow this guide here.
PRO TIP 2: Please ensure that you only have 1 connection added for that exchange and you are not importing the transactions twice. We would also recommend checking through the transactions to see if you have any duplicate manual transactions offsetting your balances.
PRO TIP 3: If the above did not help, please write to us via the app to help you further on this. To do this, go into Settings -> Support (or click here).