This issue happens when Delta does not have your full transaction history. Delta doesn't store a static balance — it calculates your holdings by replaying every transaction (buys, sells, and transfers) in chronological order.
If you move your crypto from one wallet or exchange to another, and only one of those accounts is connected to Delta, the app sees the withdrawal (the coins leaving) but not the deposit (the coins arriving). This makes the app think the coins have left your portfolio entirely, dropping your visible balance to zero.
How to restore your correct balance
Connect all your wallets or exchanges: Make sure any exchange or wallet where you currently hold or have transferred your crypto is connected to Delta (tap the "+" button and select "Connect Wallet" or "Connect Exchange Account").
Edit the transaction to a Transfer: If you prefer not to connect the other wallet, manually edit the transaction so Delta knows it was an internal move. Tap on the transaction, select Edit, and set the "Sent/Received From" or "Sent To" fields to "My Wallet" or the specific exchange — Delta will then treat it as a zero-impact internal transfer.
Disable view filters: New transactions or zero/negative balances can sometimes be hidden by display settings. Go to Settings > View Options and make sure both "Hide 0 holdings" and "Hide small holdings" are turned OFF.