Garmin hardware is great, but their software is terrible.
My friends and I had been using Garmin cycle computers and watches for a while, but lately we've been moving to Suunto and Wahoo devices - entirely due to software bugs.
My Fenix 5 watch freezes up 2 or 3 times a month. The screen will be frozen at a particular time for 5-10 minutes and it won't respond to any button presses, not even to turn it off. And they don't sync to the app without an internet connection. And the cycle computers freeze up on boot trying to download upgrades, even when you're in the midle of nowhere and haven't had an internet connection in days. Lots and lots of little annoyance bugs like those.
Definitely not designed for offline use, in any case.