.testsettings deployment section gets ignored in TFS build

I have a solution with bunch of C# projects with bunch of tests. Some of these tests require few native dlls (provided by related nuget packages). To address this .testsettings file was created that is copying dlls (that nuget coped to $(OutDir)) to test directory before running tests.

All this works fine on local machine, but when executed under TFS Build 'deployment' section of .testsettings file (or maybe entire file) gets ignored -- these dlls never materialize in test directory (nor there are any entries in the logs about them). .testsettings file is mentioned in related section of TFS build configuration.

Any ideas what could be wrong? (MSVC 2015, TFS 2013)

For TFS 2013, it only has XAML build. For XAML build, the testsetting file couldn't copy the assemblies from Nuget package $(OutDir) to the C:\Builds\...\builddefinition\...\TestSetting(tst)\...\Out folder before tests run.

I suggest that you could upgrade your TFS to TFS 2015 or upper version to use VNext build. And I have already tested that in Vnext build, it works. This is my build definition example: just add 3 steps.