There has been an ongoing issue with being unable to download a web connect file from the website for AMEX transactions. This is probably impacting primarily QuickBooks Desktop users, but I have also seen issues with delays in getting new transactions to update in QuickBooks Online. To keep monitoring this issue you can subscribe via the following link: Intuit QuickBooks Status

This web page will also show you current slowdowns and outages with various QuickBooks products including QBs Payments and Payroll.