Getting Error- We can’t find the 'Missing Data' field on the Contact object

Module -  Autolaunched and Scheduled Flows 

Trail -  Schedule a Flow

Full error message -  We can’t find the 'Missing Data' field on the Contact object. Make sure you saved the field with 'Missing_Data' as the API name.

I have created Missing Data field on contact object properly with field name as Missing_Data but how can Api name would be  Missing_Data without __c. API name will have  Missing_Data__c as its custom field. 

Any suggestion would be appreciated, thanks