Skip import for task instances with parentid = null


my import is failing when trying to import task instances. I can see in the log that the RunningUserTaskInstanceFetcher is sending a request to the bpm but the reponses all have the parentTaskId field set to null. It leads to a flowNodeId is marked non-null but is null exception.

Is it possible to filter these task instances out with a plugin? Is there any other way to import these custom tasks?

Can anyone help? Is it even possible to skip importing these task instances?