Strava is having trouble correctly uploading swimming activities from Polar Vantage M

Polar has given me an answer to my question: "Hi there, rest time information is based on the information we record with the built-in accelerometers / motion sensors in our devices. Unfortunately, at this time, it is not possible to include the motion sensor information to the file sent to Strava, and thus Strava interprets the rest times as swimming time."

I have the same problem. If I connect Polar to Strava, it takes for example 1998m instead of 2000m swim distance even if i correctly gave the length of the swimming pool. In the polar app the distance is measured correctly so its a problem when transferring the data.

The issue arises because swimming activities recorded with Polar devices do not transfer Auto-Pause information correctly to Strava. Although Polar detects pauses and adjusts the moving time internally, it does not write proper start/stop pause events into the FIT file and also does not send this metadata through its API. When Strava receives the activity, it cannot recognize where pauses occurred and therefore treats the entire session as continuous, displaying the full elapsed time instead of the actual moving time. Garmin devices, on the other hand, include explicit pause markers in their FIT files and also transmit this information via Garmin Connect during synchronization. Strava can interpret these markers correctly, which is why Garmin activities show accurate moving time and pause handling. This difference in how both brands export and sync pause events explains why Auto-Pause works reliably with Garmin but not with Polar.