You can often solve this issue by manually disconnecting the problematic account and then reconnect it from scratch.
Head to your Profile screen
Tap on "My accounts"
Tap the 3 "...", and then "Disconnect Accounts"
Once you do this, the account will be disconnected and you will be able to go in and re-add the account from scratch.
Why does this happen?
Debbie relies on Plaid, a third-party service, to link and manage connections to your financial accounts. At times, due to errors between Plaid and your bank or financial institution, disconnects can occur. Please understand that these disconnects are out of our direct control.
Important Note: If you have multiple accounts under the same financial institution that we need to de-link, be aware that it will disconnect all accounts tied to that institution. This means you will just need to select all accounts again when re-adding them.