My 66i came out of the box running software version 7.2. I have not updated it (and the release notes with the newer version do not indicate any fixes to what I am about to describe.
What I observe is that I turn on inReach tracking so it will be sending my location via satellite at regular intervals (I choose 30 minutes or 1 hour). I works for a while, but then sometime later in the day, I check and find out that it has turned itself off. There it is plain and simple without any attempt at analysis and explanation.
I will note that Leslie from Garmin has offered to look into this for me.What little discussion I stirred up on the forums suggest that Garmin somehow links inReach tracking and "activity tracking". I argue, and many agree that these should be entirely independent. Maybe they are and maybe they aren't. A suggestion is that with activity tracking active, that somehow causes the inReach tracking to get turned off, perhaps when I stop for a rest or lunch and the device notices that I am not moving. If so, I'll note that the activity tracking turns itself back on, whereas inReach tracking never gets turned back on.
Tom's backpacking pages / tom@mmto.org