Thanks for reporting this issue. It is a regression in the service front-end introduced in the April refresh that has been so far rolled out to the US Central and EU North regions (it does not repro in US EAST 2 since that region is still on the March refresh).
The team is working on a fix and will release it as a hot fix soon.
UPDATE 2017-Apr-25: The bug has been fixed and the fix has been released.
Thanks again for reporting!