Wish you could downvote the customer support replies. This is such an obvious longstanding problem on their end that Intuit's canned customer support responses are laughably transparent. 

I've tried all the suggestions for updating the bank connection, clearing the cache, etc., and still my business checking account will not update (even tho QB says it is up to date, it is most certainly not). Credit accounts are updating fine.

Fix this, Intuit. Otherwise, may an exodus of customers set you straight.