I use both Citibank and CapitalOne, and LastPass autofills for me ok on both. Citi is an issue on some of its login pages - it has at least two different ones that lead to the same services. On one of them LP fills ok, on the other it doesn't. One that works is https://online.citi.com/US/JPS/portal/Index.do
I've never had an issue with CapitalOne, though I have a savings account with them, not a credit card.
My usual advice for such issues is to delete the vault entry and add a new one. (You'll want to make note of the login details before deleting.) This generally clears up autofill problems, though not always.