@PMM828. The Accounts sheet and Balances sheet both pull data from the Balance History Sheet. If there was a recent update for this account on the Balance History tab, this institution should pull data over to the corresponding sheets.
Can you try restoring your Accounts sheet using the Tiller Labs add-on using these steps as a guide. You can restore and archive so you can reference the any categorizations you might have set up.
After restoring, can you check to see if the account shows up in the dropdown on your Accounts sheet. If so, can you also check to see if your account shows up on your Balances sheet. If it doesn’t you may need to restore your Balances sheet as well.
Let us know if that doesn’t help.