On the left hand side where my accounts show, my checking says $420
and none of my recent transactions show as imported for the last several days. However, when I go to reconcile the account, the actual balance (not $420) appears and it asks me if this is the correct balance. I have relinked this account and same thing happens.
When you reconcile and YNAB asks, "Is your current balance $x?" it's asking about the cleared balance. That's the total of all of the cleared transactions in the account.
What you're describing sounds like what I would expect to see if those recent transactions actually haven't cleared yet: YNAB is showing you the working balance ($420) in the left-hand sidebar, but when you reconcile, it asks about the cleared balance, which is unaffected by those recent uncleared transactions. If cleared balance in YNAB matches the cleared balance at Capital One, you're good to reconcile.