Sometimes I miss some fields headers on the activity page. My intervals use to be by lap, and it has space enough to be shown:
It does work if I pass the mouse over the interval/lap:
Edit to add info: It happens to me on the last version of Chrome for desktop and in an Android device (also Chrome).
I have this same issue! Happens on any activity with a lot of laps. Even when I expand the browser so there is room for the headers to fit it still won’t show unless I hover the mouse.
This should be a known bug.