I am also having this issue between Quickbooks Self-Employed Online and my American Express account. I reached out on 3/5 and they were able to reconnect it and merge past transactions, but then no new transactions synced since 3/5. I reached out again on 5/22 when i realized it was still happening & had time to spend with them. After 2 hours on the phone together the issue was still not resolved. I was emailed and given Case:15118207307, have followed up myself but received no resolution. On my American Express account page I saw this note today when I was going to download transactions but am still unable to fix it & the links are not helpful from them. PLEASEEEE provide an effect solution. https://global.americanexpress.com/activity/search?from=2023-09-01&to=2023-12-31