This is in a managed solution (production). This flow is meant to clean up some pieces after an update. The rest of the update has worked as expected.
I am getting this error message when trying to add a record to a table:
Entity 'systemuser' With Id = <GUID> Does Not Exist on Add Row in to Table.
I am not trying to do anything fancy, I am only making the value of the text upper case.

I have tried changing the connection reference to a new connection reference for the same account. I have tried deleting the step and recreating it. I deleted the ensuing unmanaged layer to ensure that wasn't the issue from the beginning. The account being used is the main (only) service account used to administer this solution.