There are a number of reasons why this could be happening, here are some possibilities.

1. The first is we only store partial submissions for a period of 30 days, once this time-frame ends the partial submission will be removed.
2. The user associated with the partial submission is attempting another submission, or has complete the submission. This new partial submission will replace the old if our servers detect this is the same user.
3. You downgraded your subscription plan. Partial Submission are exclusively available for selected pricing plans.

You cannot retrieve deleted partial submissions, nor can we display partial submissions made prior your upgrade to selected pricing plans supporting this feature.