Amazon uses a queuing system for 3rd party integrations like SureDone - which takes all requests and processes them once their queue is full or designated time has passed (usually 30 minutes).
This is why we don't get an error message right away from Amazon. Instead you always get "successfully queued for processing" - that means it made it from SD to Amazon, but then Amazon will process it at their own pace. If you got this message, the feed made it from SureDone to Amazon.
You will want to check the Amazon Logs once Amazon has processed the request to make sure there are no errors. These logs can be found in SureDone under Bulk > Logs - each file has a timestamp, which is the time the response came from Amazon to SureDone.
Because of the queuing system, sometimes it takes 3 minutes, others 30 minutes. If your upload is not getting any response for 1 or 2 hours - there may be something wrong. Try resubmitting it once and if you still have trouble please open a ticket at support.suredone.com.