Thank you for
reaching out on the community and telling us about your issue. I do apologize for the issue you're having. The best way to resolve these issues generally is to reset the cloud. This should help us get everything re synced. To do this in the top right of quicken select Edit > Preferences > Mobile and Web. You'll see troubleshooting and just to the right you'l see reset your cloud data. Select No, just reset my cloud data and type yes to confirm. After this it should begin syncing. It could take a while depending how much information you have. Once done try to do a one step update again and ideally we shouldn't see any more cloud sync error messages.
Give it a try and let us know how it goes! If it still persists we'll see what our next best step is!