How do I configure private CA with CodeBuildStep?

[boyersnet]

In our organization, we require the use of a private certificate bundle when making calls through our proxy for external resources. My various CodeBuild steps (synth, update pipeline, etc) need to utilize this certificate. I've configured the step (see code below) to retrieve the pem file from the specified bucket, but when I run cdk synth, the certificate is not listed in the CloudFormation template in the cdk.out folder and therefore the CodeBuild project is not configured with the proper certificate settings.

Here is a snippet from my Pipeline Stack. I've essentially followed the online workshop and have tried to pivot from a ShellStep to a CodeBuildStep per the documenation with no success. The EnvironmentVariables property in the BuildEnvironment is properly configured in the CloudFormation template. I'm working in a .NET 6 project and I'm running the latest version of the cdk.

var pipeline = new CodePipeline(this, id, new CodePipelineProps
      {
        PipelineName = props.ApplicationName,
        Synth = new CodeBuildStep("Synth", new CodeBuildStepProps
        {
          Input = CodePipelineSource.Connection(
                repo,
                branch,
                new ConnectionSourceOptions
                {
                  ConnectionArn = connectionArn
                }),
          BuildEnvironment = new BuildEnvironment
          {
            EnvironmentVariables = BuildArtifactoryEnvironmentVarabiles(SecretArn),
            Certificate = new BuildEnvironmentCertificate
            {
              Bucket = Bucket.FromBucketName(this, "SharedResourceBucket", props.SharedResourceBucket),
              ObjectKey = props.CertificateObjectKey
            }
          },
          Vpc = vpc,
          SecurityGroups = new ISecurityGroup[] { sg },
          SubnetSelection = new SubnetSelection { Subnets = new[] { subnetAz1AMgmt, subnetAz1BMgmt } },
          Commands = BuildSynthCommandList(),
          PrimaryOutputDirectory = "CDK/cdk.out",
          RolePolicyStatements = GetCodeBuildPolicies(SecretArn, props.SharedResourceBucket, props.CertificateObjectKey),
        })
    });