FR165 music goes into standbye during run

I did a run with navigation and music (Spotify) and every 5 minutes,  the watch tries to go to standbye (it warns 30 seconds before). I didn't get to wake it up during these 30s and all data was lost which is unacceptable.

I know I can adjust the standbye time from 5 to 25 minutes but the question is why does the watch even try to go into standbye?

The manual says "after X minutes of inactivity" but clearly there is no inactivity as I'm navigating, tracking my run and listening to music.

(During the run there is no connection to Garmin Connect and the battery was full.)