It's still confirming. Deposits need blockchain confirmations, then pass our standard checks. Your deposit can show as confirmed shortly before it's added to your balance.
The tag or memo was missing. For XRP, Stellar and TON, a deposit without the tag can't be matched to your account automatically. Contact support with the transaction hash.
It was sent on the wrong network. Funds must be sent on a network Oobit supports for that asset, to the matching address.
It was under $0.10. Very small deposits aren't processed.
The asset isn't available where you live. Some assets aren't supported in certain countries or US states, and deposits of those assets aren't added to your balance.
If none of these apply, contact support with the transaction hash, asset and network.