Hey there Nospam,
Thankyou for sharing your issue in a detailed explanation.
With regards to this it sounds like because you have set a custom workout it's just basically switched off the announcements but no worry this can be fixed by following the steps below.
On Your iPhone:
- Open the Watch app
- Go to Workout > Workout View > Voice Feedback
- Make sure Voice Feedback is ON
- Then check Pace/Distance Announcements and turn on Distance Alerts
On Your Apple Watch (during a workout):
- Start your custom interval workout
- Swipe to the settings/options screen (three dots or "•••")
Scroll down and look for Alerts or Metrics Alerts
Turn on Distance and set it to Every 1 km
Optional: Adjust What It Announces
- Go to Workout > Alerts > Distance and choose what gets read aloud (e.g. pace, time, heart rate).
After this, your watch should announce pace at every kilometre again — even inside an interval-based custom workout.
Important Note
If you have both interval alerts and distance alerts, watchesOS will play both — so you may get two announcements close together if an interval ends right at a kilometre mark. This is normal.
Feel free to reply if you need any additional support.