Symptoms
Some InfoPath process instances got deleted in K2. The auditing tables indicated that the instances were deleted by the K2 service account. Is there a way to restart InfoPath processes?
Diagnoses
In this case, a custom rule on the form prohibited a new instance from being started i.e. the rule was blocked by a SharePoint column that we could not work around.
Editing the template to allow the rule to be bypassed is also not a good option since the XML form previously submitted has processing instructions to always open in the template it was created on so this would have required additional work to be performed to get the form to open the in the new template.
The easiest way would be to resubmit a new form with the data of the old form.
Resolution
New instances were started by resubmitting via InfoPath with the same data.