CANNOT_EXECUTE_FLOW_TRIGGER Issue in Trailhead Challenge

Building in Process Builder - https://trailhead.salesforce.com/trails/force_com_admin_intermediate/modules/business_process_automation/units/process_builder

Scenario from Admin Intermediate Challenge (Trailhead)

-           Create a process on the Account object that updates the child’s Contact addresses when an account's address is updated.

Current Flow Chart

Step 1 – Naming the Process

Step 2 – Setting the Object

3 – Setting Immediate Action – conditions to identify when the parent Account shipping address field values are updated

4 – Setting updated targets – to sync the mailing data with the Parent ID’s account data

My test resulted in a CANNOT_EXECUTE_FLOW_TRIGGER and I reviewed the debug logs for the test environment and do not see any entries and stuck on where the issue is in my logic.  This is the error message:

There was an unexpected error in your org which is preventing this assessment check from completing: System.DmlException: Insert failed. First exception on row 0; first error: CANNOT_EXECUTE_FLOW_TRIGGER, The record couldn’t be saved because it failed to trigger a flow. The flow couldn't find the myVariable_old resource. Contact your administrator for help.: []

Please advise.

-cmb