Symptoms
You process an ADO.NET Provider for Host Files provider against a z/OS dataset record. If the provider contains a SELECT statement that contains a discriminated union, the provider fails.
In this situation, you receive no error message.
Resolution
This problem is fixed in Cumulative Update 1 for Host Integration Server 2016.
Status
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
References
Learn about the terminology Microsoft uses to describe software updates.