GitHub Webhook is not getting created by CloudFormation

Hello!

I'm having a strange problem with CloudFormation not creating a GitHub Webhook on a specified repository. What makes it strange is that stack is getting created successfully with AWS::CodePipeline::Webhook resource marked as "CREATE_COMPLETE" without raising any errors. However, when I open the GitHub repository settings I can't see a webhook and CodePipeline is not getting triggered on commit.

The resource is defined this way:

PipelineHook:
  Type: AWS::CodePipeline::Webhook
  Properties:
    Name: !Ref StackName
    Authentication: GITHUB_HMAC
    AuthenticationConfiguration:
      SecretToken: !Ref GitHubWebhookSecretToken
    Filters:
      - JsonPath: $.ref
        MatchEquals: refs/heads/{Branch}
    TargetPipeline: !Ref Pipeline
    TargetPipelineVersion: !GetAtt Pipeline.Version
    TargetAction: github-clone

  Pipeline:
    Type: AWS::CodePipeline::Pipeline
    Properties:
      Name: !Ref StackName
      RoleArn: !GetAtt PipelineRole.Arn
      ArtifactStore:
        Location: !Ref ArtifactStoreBucket
        Type: S3

      Stages:
        # Downloading source code from GitHub repository
        - Name: source
          Actions:
            - Name: github-clone
              RunOrder: 1
              ActionTypeId:
                Category: Source
                Provider: GitHub
                Owner: ThirdParty
                Version: "1"
              Configuration:
                Owner: !Ref GitHubOwner
                Repo: !Ref GitHubRepo
                Branch: !Ref GitHubBranch
                OAuthToken: !Ref GitHubAccessToken
                PollForSourceChanges: false
              OutputArtifacts:
                - Name: source-code

        # Building a Docker image and pushing it to ECR
        - Name: stage
          Actions:
            - Name: stage-build
              RunOrder: 1
              InputArtifacts:
                - Name: source-code
              ActionTypeId:
                Category: Build
                Provider: CodeBuild
                Owner: AWS
                Version: "1"
              Configuration:
                ProjectName: !Ref BuildProject

I've tried to call GitHub's API directly to create a hook using the same AccessToken and it worked correctly:

Accept: application/vnd.github.v3+json
Content-Type: application/json
Authorization: token ...
{
	"config": {
		"url": "https://www.example.com",
		"content_type": "json",
		"secret": "..."
	}
}

Also, the same exact configuration was working correctly in another stack.