VSTS Test Parallel Test Run with NUnt3 Test

I am having some issues trying to get NUnit3 test to execute via VSTS VSTest in parallel, and looking for input on what could be wrong.

We have a solution that is and Automation Test Suite of Selenium Web UI Test for our product. This solution uses NUnit3 framework. All of our test classes are affixed with [TestFixture] Attribute and all of our methods are affixed with the [Parallelizable] Attribute.

When we execute the test locally in VS15 the test execute in parallel without a problem.

When we create a build / step in VSTS to execute the test using the NUnit3TestAdapter.3.10.0 the test are loaded and executed in a non-parallel fashion, even though they are attributed with the parallel attribute. We are executing all test in a single dll that is output when the project is built.

Is there something i am missing? Do we need to offload this to a test agent to get the parallel execution?

Any assistance would be greatly appreciated.