Azure DevOps Code Coverage for .NET Core 3.1

Finally got it working with the help of a Microsoft MVP. Sharing the code from the test segment that worked.

     - task: DotNetCoreCLI@2
        displayName: "dotnet global test tool install"
        inputs:
          command: 'custom'
          custom: 'tool'
          arguments: 'install --global dotnet-reportgenerator-globaltool'

      - script: dotnet test WebApp.Web.Tests/WebApp.Web.Tests.csproj --logger "trx;LogFileName=testresults.trx" /p:CollectCoverage=true /p:CoverletOutputFormat=cobertura /p:CoverletOutput=$(Build.SourcesDirectory)/TestResults/Coverage/
        displayName: 'dotnet test'

      - script: reportgenerator "-reports:$(Build.SourcesDirectory)/TestResults/Coverage/coverage.cobertura.xml" "-targetDir:$(Build.SourcesDirectory)/TestResults/Coverage/Reports" -tag:$(Build.BuildNumber) -reportTypes:htmlInline
        workingDirectory: $(Build.SourcesDirectory)/WebApp.Web.Tests
        displayName: 'dotnet reportgenerator'
      - task: PublishTestResults@2
        inputs:
          testRunner: VSTest
          testResultsFiles: '**/*.trx'
          failTaskOnFailedTests: true

      - task: PublishCodeCoverageResults@1
        inputs:
          codeCoverageTool: 'cobertura'
          summaryFileLocation: $(Build.SourcesDirectory)/TestResults/Coverage/**/coverage.cobertura.xml
          reportDirectory: $(Build.SourcesDirectory)/TestResults/Coverage/Reports
          failIfCoverageEmpty: false 

Resources that helped can be found here

The accepted solution got me close, but I had issues with installing the tool globally. The PATH gets updated in a global install, but is never reloaded so the reportgenerator could not be found. Making the following changes took care of that:

 task: DotNetCoreCLI@2
  displayName: 'Install dotnet-reportgenerator-globaltool'
  inputs:
    command: custom
    custom: tool
    arguments: install --tool-path . dotnet-reportgenerator-globaltool

- task: DotNetCoreCLI@2
  displayName: 'Test $(buildConfiguration)'
  inputs:
    command: test
    projects: $(solution)
    arguments: --configuration $(BuildConfiguration) --collect "XPlat Code Coverage" 

- script: ./reportgenerator -reports:$(Agent.TempDirectory)/**/coverage.cobertura.xml -targetDir:$(Build.SourcesDirectory)/TestResults/Coverage/Reports -reporttypes:Cobertura
  displayName: 'Create Code Coverage Reports'

- task: PublishCodeCoverageResults@1
  displayName: 'Publish Code Coverage'
  inputs:
    codeCoverageTool: Cobertura
    summaryFileLocation: $(Build.SourcesDirectory)/TestResults/Coverage/Reports/Cobertura.xml
    failIfCoverageEmpty: false