coverlet: Coverlet does not generate code coverage

Main Error

After running tests coverlet generates empty cobertura xml file on my build agent

Agent

Azure Devops - Hosted Agent

Issue Description

I’m following a SO post to generate a cobertura code coverage report on a .Net Full Framework 4.7.1.

https://stackoverflow.com/questions/54627918/view-code-coverage-report-on-azure-devops-portal/54738732#54738732

I’m using coverlet to run ‘dotnet vstest’ and then generate a coverage.cobertura.xml file. This is working on my local machine but when running on the build agent the coverage xml file is just empty of results.

My yaml build step

- powershell: |
        "install tools:"
        &dotnet tool install coverlet.console --tool-path . --version 1.5.3

        "`nrun tests:"
        $unitTestFile = gci -Recurse | ?{ $_.FullName -like "*bin\*test.dll" }
        Write-Host "`$unitTestFile value: $unitTestFile"

        $coverlet = "$pwd\coverlet.exe"

        "calling $coverlet for $($unitTestFile.FullName)"
        &$coverlet $unitTestFile.FullName --target "dotnet" --targetargs "vstest $($unitTestFile.FullName) --logger:trx" --format "cobertura"

Log output:

calling C:\__w\9\s\coverlet.exe for C:\__w\9\s\Source\Server.Net\ActivityCalendarSvc\ActivityCalendar.Test\bin\Release\ActivityCalendar.Test.dll 
Microsoft (R) Test Execution Command Line Tool Version 16.2.0-preview-20190606-02
Copyright (c) Microsoft Corporation.  All rights reserved.
  
Starting test execution, please wait... 
! TestRecurringEntryTestData [895ms]  
! TestDetailsMissing [5ms] 
! TestSplitEvents [4ms]
Results File: C:\__w\9\s\TestResults\ContainerAdministrator_E1968FE75CB5_2019-08-19_10_52_23.trx   
   
 Test Run Successful. 
 Total tests: 19 
 Passed: 16 
 Skipped: 3 
 Total time: 2.4672 Seconds 

 Calculating coverage result... 
 Generating report 'C:\__w\9\s\coverage.cobertura.xml' 

  | +--------+--------+--------+--------+ |  
  | Module \| Line   \| Branch \| Method |  
  | +--------+--------+--------+--------+ |  

  | +---------+--------+--------+--------+ |  
  |        \| Line   \| Branch \| Method  |  
  | +---------+--------+--------+--------+ |  
  | Total   \| 100%   \| 100%   \| 100%    |  
  | +---------+--------+--------+--------+ |  
  |  Average \| ∞%     \| ∞%     \| ∞%     |  
  | +---------+--------+--------+--------+

Since it does run the tests correctly, and I’ve viewed the trx file, what could be causing it to not outputting any code coverage data?