When a pipeline gets to an "input" step, the blue pipeline UI doesn't give any apparent way to approve the input, and so the pipeline just hangs.

Also, when input is the first thing to happen in a pipeline, the UI appears that it hasn't loaded anything and is just waiting.

Example pipeline snippets:

stage ('s1') {
  echo 'this is stage 1'
}

stage ('s2') {
    echo 'this is stage 2'
    input id: 'Approve', message: 'Approve', ok: 'Yes'
}

stage ('s3') {
    echo 'this is stage 3'
}