Hi NK2020,
I'm sorry to hear you've had some trouble with bank feeds. Between all of the different banks that are supported, and all of the connection requirements, there can be a number of different reasons that bank feeds can stop working. We do have tools that allow us to verify the cause of the issue and guide you to a solution, however there can be a number of reasons why the connection could stop working; the best option if you're unable to see the cause for the issue is to reach out to our support team so that they can diagnose and resolve it with you if possible as the issue experienced by other users may not be the same as yours.
With that said, if there are missing historical transactions, uploading a CSV file is certainly a quick way to bring the transactions into the Banking tab so they can be reviewed. If required, this article has some tips on importing, and this article also has a video for reference.
-Kass
