There's a few reasons why some of your accounts aren't showing up to connect with QuickBooks:
Your bank is conducting system maintenance.
The financial institution may not be a participating bank.
Your bank might not connect to all types of accounts. For example, personal accounts vs business accounts.
Some banks have multiple names on our list. You might want to check if there's any other titles they go by. You can also try all possible website URLs for them.
I'd recommend initially reaching out to your bank to confirm if there's any maintenance going on. If all seems well on their end, try clearing the browser's temporary internet files. It's possible these could be interfering with your search results displaying when you're searching for the accounts in QuickBooks.
If you still can't find the bank accounts and would like to import transactions, you can manually upload them.
Here's how get what you need:
In your left navigation bar, go to Accounting, then Chart of accounts.
Find the account you want to upload transactions into and click its View register option.
Locate your account's oldest transaction and write down its date.
Usually, an account's oldest transaction is its opening balance.
Sign in to the financial institution's website.
Follow their instructions for downloading CSV/QBO/QFX files of transaction data to your computer.
Check the date range for your download. It should be at least one day before the date of your oldest transaction mentioned in step 3.
Download the transactions. Save your file somewhere you can easily find it, like the computer's Desktop screen.
Open and review your file's format and size. Make sure it's formatted correctly before uploading it. The maximum file size is 350 KB. If your file's too big, try shortening the date range and download transactions in smaller batches.