Apple Watch Ultra 1 – GPS track missing in structured/custom workouts

Hi,

I have a first-generation Apple Watch Ultra and recently noticed a recurring issue with GPS tracking in structured/custom workouts.

I regularly run planned interval workouts that include a warm-up, multiple fast/slow intervals, and a cooldown. Until recently, GPS tracking worked fine. However, in the past week I have experienced missing GPS route data in the Health/Fitness app:

• 2025-08-07 (06:24–07:47) – No GPS data recorded at all.
• 2025-08-09 (06:29–08:44) – Only the first 20 minutes (warm-up) show GPS data, then nothing until a short segment about 50–60 minutes later.

Workouts were created as structured runs with intervals, including a short rest period.

What’s strange is that free runs still record GPS perfectly. The problem only appears in pre-planned structured workouts, and it seems to happen after a rest interval is included.

I found at least one similar report here on Apple Community describing the same GPS issue in custom workouts:

Apple Watch losing map during custom work… - Apple Community

Screenshots attached for the affected workouts.

Has anyone else experienced this? Could this be a known watchOS bug?

Thanks in advance.

[Edited by Moderator]