Thanks for the post and great question! This sounds like a privacy rule issue. I recognize that you’ve set the backend workflow to ignore privacy rules, but they could still be effecting your ability to successfully schedule the workflow at the start.
By any chance, are you using a schedule on a list action on the front end? If so, this is happening outside the run of the actual backend workflow and if the list of items are protected by privacy rules, you wouldn’t be able to find records to pass in successfully.
If you need to find the records, and they’re protected, you could also handle the search on the backend as well. An easy way to do this would be to have two backend workflows. One that acts as a trigger, does the search and schedules the existing backend workflow on the resulting list.
Give it a try and don’t hesitate to reach out with any additional questions to [email protected]