HashPack gathers the next reward data for your account directly from the Hedera network. If you have staked for more than 48 hours, check that you haven't automatically claimed your rewards already.
If you do not see any staking rewards but think you should have, please contact Hedera support. HashPack does not determine the available rewards and only displays what is provided by the network. An alternative way to check your staking rewards is through connecting your wallet on HashScan.