Could an internal exchange transfer be absent from the public blockchain?¶

Yes. A custodial exchange can transfer value between customer ledger balances without moving assets between blockchain addresses, so a genuine completed transfer may have no transaction hash.

Provider custody enables off-chain settlement¶

The exchange controls pooled keys and adjusts internal entitlements. Later operational wallet movements may be unrelated to the individual customer event. Internal records can identify sender and recipient accounts, reference, asset, amount, fee, status, times, endpoints and authentication.

Prove the ledger event through the provider¶

Preserve platform, both account IDs, internal reference, asset, amount, time and linked messages. Ask whether the event was a transfer, trade, adjustment or withdrawal and compare access records and any later cash-out.

Absence from an explorer does not disprove the event, while the ledger entry alone does not identify either human operator.