If you launch more than 10 downstream job from a pipeline the Blueocean visualization hands, and it is not possible to see the results of all downstream jobs, it is easy to replicate

1- Create a Pipeline job dummy

node {
   echo 'Hello World'
}

2- Create a Pipeline job trigger dummy

pipeline {
  agent any
  stages {
    stage("test") {
      agent any
      steps {
        sh 'export'
        script{
          for(def i =  0; i < 10; i++){
            build(job: "dummy")
          }
        }
      }
    }
  }
}

3- build Pipeline job trigger dummy
4- Go to the Blueocian build view of that build
5- The Bluocean view stuck and the browser tab hands, there is no errors in the javascript console nor developer tools network tab