I frequently use the daily suggested workouts, and have noticed that during a Rest interval (for example, sprints), the screen that shows the Rest timer (until the next interval) does not actually show which interval number you are running (like 2/8 to show that you are in the second of eight intervals)
I am quite certain this used to be part of the display. Was this removed? Is it a bug?
If the actual running intervals are very short, like 10 second sprints, you really don't have an opportunity to see what interval number you are in unless you look at the screen while running the 10 second spring, or see the temporary transition screen.
EDIT: This is on version 21.19, but I have observed this on several versions going back around a year.