Azure devops - NUnit tests not found when outside of a netcore/template project

I followed the tutorials in the docs for azure devops with regards to running Selenium tests as part of the build.

My local tests run fine with the browsers I have webdrivers installed for, but when the VSTest task runs, it doesn't unpack any tests from anything under NUnit attributes.

Now a few things to point out with my project structure:

1. The test project started out as a basic Visual Studio 2017 Unit Test template, with MS Test.
2. I preferred NUnit, so I am writing/rewriting the tests using that framework instead of the MSTest it was created with.

My current azure devops pipeline config:

Working local tests setup:

Now, I can easily add a new project using the NUnit template which for whatever reason allows the azure build to see these tests, but that causes my project structure to change and it defaults to netcoreapp2.1 instead of 4.6, and then the azure build can't find all sorts of stuff.