tooltip - highlightDataSeries, not working on line charts?

[easyperl]

Based on the documentation, I was guessing this would work on multi-series line charts as you mouse over a series line... the tooltip would show all the items but basically grey out all the other series but the one you were mousing over. Perhaps something like this you might see on google analytics:

I was also hoping it would highlight the line for just the series you moused over as well, like when you mouse over the legend (and also exampled in the screen shot (where one series line is obviously the focus).

Instead, I don't see any behavior change at all for a line chart when set to true or false. I looked into the code on github and it appears this only works for bar charts (??) and only in certain situations... but references for the check in seem to relate to issue #599 which isn't 100% related to what I am looking for. I tried several minimal tests on codepen before actually looking at the code and seeing the barchart condition. I even tested with bar charts and I am not sure what it is doing different using true and false reloads.

Is this functionality somewhere else? Am I missing something? Should I put in a bug (based on docs) or enhancement (based on my functionality desire) request?