stryker-net: Stryker cannot find tests on project

Trying to get stryker to run on a VisualStudio 22 unit test project.

The unit test project uses .NET framework 4.8 with MSTest.TestFramework 2.2.10 The referenced project (engine) uses .NET framework 4.5.1

Then running

dotnet stryker --test-project Engine.Tests/Engine.Tests.csproj -p Projects/Engine/Engine.csproj -s Engine.sln

It looks like all is al right but then:

[14:16:28 INF] Analysis complete.
[14:16:28 INF] Building test project Engine.Tests\Engine.Tests.csproj (1/1)
[14:17:08 INF] Total number of tests found: Unable to detect

The tests can be started from Visual Studio so they absolutely exist.

Example test:

[TestMethod]
public void TestFMSShippingCostsInvalidDeliveryType()
{
    var c = new ShippingCosts();

    Dealer dealer = new Dealer {
        SendByMail = false,
    };

    c.IsValidOrder(dealer, DateTime.Today).Should().BeFalse();
}

What to do to get stryker to find these tests?

Logs

[14:16:28 INF] Building test project Engine.Tests\Engine.Tests.csproj (1/1)
[14:17:08 INF] Total number of tests found: Unable to detect

Expected behavior

stryker finds tests

Desktop (please complete the following information):

• OS windows 10
• Type of project: unit test assembly dll
• Framework Version 4.8, 4.5.1
• Stryker Version latest