There is another post mention this. It seems that Zepp doesn‘t provide laps for intervals, but does it for strava.
What you can try:
1 Check if there are laps with: Action → Use Laps
If there are laps, consider setting the „Use Laps“ and „Keep all laps“ option in the settings box of your activity type.
2 If there are no laps, use your workout as laps: Action → Analyze → Check the “Use workout steps for laps” and uncheck all other checkboxes.