Marketo's list upload API can fail at times, however, it doesn't provide alerts that the list upload process has failed. If you receive an alert from Seventh Sense that there are delivery failures, you'll want to check the error in the log that is attached to the email.
If you see an error code of 1019 with the message "Import is in progress", this is a good indicator that the list upload process has silently failed. When this occurs, subsequent list uploads to the campaign will fail unless you stop the failed list upload.
Below are steps you can take in Marketo to stop a list upload. Once the list upload is stopped, you do not need to take any corrective measures as Seventh Sense will retry the failures as long as the delivery window is still open.
1.) From the delivery list in Marketo, under list actions, select “show import status”.
2.) The import status will look like this:
3.) Click stop. It should pop up a confirmation dialog.
4.) The import status should indicate the import was cancelled.