AWS::CodePipeline::Pipeline - RestartExecutionOnUpdate - Pipeline is not restarted after modification of AWS::CodeBuild::Project Buildspe

Looking for guidance on the CodePipeline feature to RestartExecutionOnUpdate. Using the cdk we are able to modify the pipeline, however, when the modification changes a buildspec within a CodeBuild action, then the pipeline is not restarted. Is this expected behavior?

In the example below, the CodePipeline has been deployed with the cdk constructs. Then in a subsequent commit a new change occurs within a buildspec and is later redeployed by the pipeline, however the pipeline does not restart for a codebuild buildspec change Example code:

const pipeline = new Pipeline(this, 'Pipeline-' + branch, {
      restartExecutionOnUpdate: true,
      pipelineName: repo_name + branch,
    } )
    
    // add a source stage
    const sourceStage = pipeline.addStage({
      stageName: 'Source',
    });
    const sourceOutput = new Artifact();
    const sourceAction = new CodeStarConnectionsSourceAction({
      runOrder: 1,
      actionName: 'BitBucket_Source',
      owner: 'funsystems',
      repo: repo_name,
      branch: branch,
      output: sourceOutput,
      connectionArn: 'arn:aws:codestar-connections:us-east-2:bla',
    });

    sourceStage.addAction(sourceAction)

    const lightCheckProject = new PipelineProject(this, `LightCheckProject`, {
      projectName: `${repo_name}-${branch}-LightCheck`,
      buildSpec: BuildSpec.fromObject({
        version: '0.2',
        phases: {
          build: {
            commands:[
              'mkdir results',
              'echo "some test results" >> results/test_one.txt',  // existing 
              'echo "some test results" >> results/test_two.txt',  // added and deployed in a later stage of the pipeline
            ],
          },
        },
      }),
    });

    // add a stage
    const buildStage = pipeline.addStage({ stageName: 'Build' });
    const codeBuildAction = new CodeBuildAction({
      role: codepipelineRole,
      project: lightCheckProject,
      actionName: "unit",
      input: sourceOutput,
    })
    buildStage.addAction(codeBuildAction)