Visual Studio 2019 and Visual Studio 2017 Tests conclude differently

I am migrating from VS 2017 to VS 2019.

I have a solution that has some tests and they behave differently on different versions of Visual Studio:

VS 2017 Version: 15.9.16:

VS 2019 Version: 16.3.6:

Steps i take:

1. Open VS.
2. Clean the Solution.
3. Run the tests.

What's also interesting, is that if i re-run the tests individually on VS 2019, they all pass.

Testing framework: Microsoft Visual Studio Unit Test Framework. Version: 10.0.0.0

Errors from VS 2019 are: Assert.IsTrue Failed, Assert.IsNotNull Failed, NullObjectReference Exception

Failing tests are always the same. The solution is the same, only the IDE is of a different version.

How would i go about locating the issue for this?

This is a potential source of a lot of confusion for my teammates.