Appveyor runs tests but OpenCover doesn't show coverage - visual-studio-2017

Question

I am building the project and running test cases in appveyor. After successfully executing test cases the coverage data must be uploaded to coveralls.
But in my case no error is thrown but coverage is being recorded.
The details of my project are
.Net Core 1.1.0
Visual Studio 2017
xunit - 2.2.0
OpenCover - 4.6.519
coveralls.net - 0.7.0
My appveyor.yml is as below :
version: 1.0.{build}
os: Visual Studio 2017
skip_tags: true
configuration: Release
environment:
nodejs_version: "0.12"
COVERALLS_REPO_TOKEN:
secure: rstgrtert
cache:
- "%LOCALAPPDATA%\\Yarn"
install:
- npm i -g yarn#0.16.1
- npm i -g typescript typings
- yarn global add typescript typings
- cd ".\Promact.Oauth.Server\src\Promact.Oauth.Server\"
- yarn
- cd..
- cd..
build_script:
- ps: dotnet restore
build:
project: .\Promact.Oauth.Server\Promact.Oauth.Server.sln
verbosity: minimal
test_script:
- cd ".\src\"
- ps: >-
C:\Users\appveyor\.nuget\packages\OpenCover\4.6.519\tools\OpenCover.Console.exe-target:"C:\Program Files\dotnet\dotnet.exe" -targetargs:"test -f netcoreapp1.1 -c Release .\Promact.Oauth.Server.Tests\Promact.Oauth.Server.Tests.csproj" -mergeoutput -hideskipped:File -output:opencover.xml -oldStyle -filter:"+[Promact.Oauth.Server]*Repository -[Promact.Oauth.Server.Tests*]*" -register:user
if(![string]::IsNullOrEmpty($env:COVERALLS_REPO_TOKEN)){
$coveralls = (Resolve-Path "C:\Users\appveyor\.nuget\packages\coveralls.net\0.7.0\tools\csmacnz.coveralls. exe").ToString()
& $coveralls --opencover -i opencover.xml --repoToken
$env:COVERALLS_REPO_TOKEN --commitId $env:APPVEYOR_REPO_COMMIT --commitBranch $env:APPVEYOR_REPO_BRANCH --commitAuthor $env:APPVEYOR_REPO_COMMIT_AUTHOR --commitEmail $env:APPVEYOR_REPO_COMMIT_AUTHOR_EMAIL --commitMessage $env:APPVEYOR_REPO_COMMIT_MESSAGE --jobId $env:APPVEYOR_JOB_ID
}
In appveyor it runs the test and simply shows
Committing...
No results, this could be for a number of reasons. The most common reasons are:
1) missing PDBs for the assemblies that match the filter please review the
output file and refer to the Usage guide (Usage.rtf) about filters.
2) the profiler may not be registered correctly, please refer to the Usage
guide and the -register switch.
Coverage data uploaded to coveralls.
link to the appveyor build