Hello,
in the activity details view, the heart rate chart does not change when you select "%Max" or "Zone".
In the classic view it was working properly, and selecting "%Max" or "Zone", the chart display was changing too to display the selected. In the modern view does not change anymore.
The Timing chart, on the other hand, change from "pace" to "speed" depending from the selection, which I believe should be the correct behaviour.
Thanks and regards,