NUnit3 tests don't run on TFS build

we are currently migrating our unit tests from using MSTest to NUnit (version 3.2.1) but are having problems running the NUnit tests from our TFS .xaml build definition. The TFS build definition is using the rule "Run tests in assemblies matching **\*.test*.dll". For my NUnit test project I have downloaded, installed and referenced the following NuGet packages:

1) NUnit v3.2.1

2) NUnit3TestAdapter v3.0.10

Executing my tests within VS (test explorer) works perfectly, and I thought that these steps would be enough to ensure they were also run as part of the CI build on TFS, however the tests are never executed. I have no error/warning/message pertaining to these tests in the diagnostic output, however I do see that the build process has detected my assembly as a candidate for unit tests seeing as it matches the aforementioned wildcard rule (**\*.test*.dll).

I also tried putting the NUnit3TestAdapter assemblies in the "Version control path to custom assemblies" folder defined in the build controller properties for TFS but to no avail.

Can anyone see if I am missing a step in the process here. From all that I have read on these forums I seem to have done everything necessary but they still don't execute. Regards.