Collecting code coverage prevents all test discovery on net472 only

This repros locally and in Azure Pipelines builds.

git clone https://github.com/AArnott/Xunit.StaFact.git
cd Xunit.StaFact\src
git checkout 6d1a5e6023f612ad00d2e00f5204f362dc0a71ce
dotnet test --filter "TestCategory!=FailureExpected" -v n /p:CollectCoverage=true

Notice how net472 runs 0 tests and reports:

+---------------+------+--------+--------+
| Module        | Line | Branch | Method |
+---------------+------+--------+--------+
| Xunit.StaFact | 0%   | 0%     | 0%     |
+---------------+------+--------+--------+

+---------+------+--------+--------+
|         | Line | Branch | Method |
+---------+------+--------+--------+
| Total   | 0%   | 0%     | 0%     |
+---------+------+--------+--------+
| Average | 0%   | 0%     | 0%     |
+---------+------+--------+--------+

While the netcoreapp targets report non-zero results:

+---------------+--------+--------+--------+
| Module        | Line   | Branch | Method |
+---------------+--------+--------+--------+
| Xunit.StaFact | 86.44% | 62.19% | 78.33% |
+---------------+--------+--------+--------+

+---------+--------+--------+--------+
|         | Line   | Branch | Method |
+---------+--------+--------+--------+
| Total   | 86.44% | 62.19% | 78.33% |
+---------+--------+--------+--------+
| Average | 86.44% | 62.19% | 78.33% |
+---------+--------+--------+--------+

In fact simply comparing the output of these two commands shows that the mere collection of code coverage is what blocks test discovery:

 dotnet test --filter "TestCategory!=FailureExpected" /p:CollectCoverage=true -f net472 
 dotnet test --filter "TestCategory!=FailureExpected" -f net472 

[saucecontrol]

I’m getting similar results with this project: https://github.com/saucecontrol/Blake2Fast/tree/azure-coverage

What I’ve found is that when I run locally, I get correct results with netfx target on 32-bit

dotnet test tests\Blake2.Test -c Coverage -s tests\runsettings --logger trx

with the following runsettings:

<RunSettings>
    <RunConfiguration>
        <TargetPlatform>x86</TargetPlatform>
        <DisableAppDomain>true</DisableAppDomain>
    </RunConfiguration>
</RunSettings>

However, if I switch to <TargetPlatform>x64</TargetPlatform>, I get 0% coverage.

On Azure Pipelines, I get 0% coverage under either config.

The netcore targets are correct no matter how I run.

[jasells]

will do.