Tried again from scratch (reinstalling widget/whole app) and is still happening.
I may contact support to get it fixed since I just wont to be sure that mine is not a defective unit.
Just in case it helps…
Same problem here as well. My 735XT is from Feb 2019 and the software is up to date. Step and HR reset after each reboot, which happens 5-10 times a day.
I have the same problem too. I bought my 735xt brand new in Sept. 2020 (5 months ago). During this 5 month period I've had two separate episodes that lasted for 2-3 days of the watch spontaneously restarting on its own. I've restarted the watch using the "power button" and holding for 15 seconds several times. This does not help. This issue is very disruptive as the watch could restart on you during an activity (which is why I bought this watch in the first place is to accurately track activity data!!!). Garmin needs to pair with Apple to get a better operating system figured out.