I understand that the ansiColor plugin and step, as of 0.6.0, when applied, will permit ansi-coloured console data to be correctly displayed for both blue ocean console and classic views. We are very grateful for that. We use blue ocean in our team and I found that to work as described.
Now, when viewing a pipeline, whenever there is too much logging to fit in a blue ocean console, it is truncated, and a clickable button to 'show complete logs' appears near the top. When this is clicked, you get a log file displayed in the web browser. It is this log view that I am referring to. A similar log view can be found by clicking the 'pop out' symbol above and to the right of the output section in blue ocean. There is also something known as pipeline.log which can be found when you click on the artifacts tab on blue ocean which is simply the summation of all the output across the pipeline in the same format as the aforementioned logs.
All of these log views seem to contain the ansi-color symbols even when the ansiColor plugin and step are in use.
After chatting with Jesse Glick regarding the related Jira
JENKINS-41200 and the related improvement to the ansiColor plugin https://github.com/jenkinsci/ansicolor-plugin/pull/132, he advised that this was a blue-ocean issue and that it was not part of the scope of the previous work in this area.