When you first create a bank-connected account in Wallet, your entire transaction history will not be downloaded. Wallet should download your bank transactions for the past 90-180 days (depending on the specific bank).
If you connect your previously bank-connected account in Wallet again, your transactions will still be downloaded, but only up to the most recent transaction previously taken from your bank.
You could try adding older transaction by using our Import feature on the Web:
1. Import your file
2. Erase Import file in mobile app
3. Sync with bank