Are you using Android? Last I checked it showed nonsense for these dates.

https://github.com/amp64/sonosbugtracker/issues/32

I believe the iOS gets it right, but cannot verify right now.

My Windows/Xbox app also shows them, in fact I used them as the test case as I couldn’t find any other service that emitted that particular metadata.

I’m on the Android app, it only shows the duration.