Sometimes funds are not immediately visible and accessible
It always takes a certain amount of time before they reach their final destination address and are usable.
Consider :
- The length of time it takes for the transaction to be processed by a centralized exchange.
- The number of transactions possible per second by the network/blockchain used.
- The possible congestion of this network/blockchain.
- Transaction fees manually lowered by the user and therefore implying a lower priority for processing the transaction.
Note that you can track your transaction via its ID and an associated blockchain explorer.