645M Freeze after FW 6.20

Exactly the same here. I do not know which firmware I had before, but only after recently updating to 6.20 the watch seemingly freezes after a training. It seems to be stuck during saving: Two occurences since the update:

1. Screen kept stuck during save for minutes. Despite the freezing the watch still synched the activity to Strava (WiFi connection available ~20 min after starting saving, screen still freezing then).

2. Pressed Save after an activity. Then again the screen was freezing for ~2 min ... and finally returned to the main watch face.

In both cases the time shown on the main watch face did not change. Both times I did a soft reset (press "Light" for 15 secs) which seemed to solve the issue: The the time on the watch face was progressing again, it showed the wrong time (a couple of minutes behind the real time). Finally fixed this by setting the time (via GPS sync).

This issue is definitely really annoying! It'd be very pleased if you could solve this issue. Hopefully this helps in tracking down this bug. Please let me know if you need any further information.

Not sure if related: The scope of the "last week" (as seen on the main watch face and on the widget showing details of the last run) seems to be miscalculated: It seems to keep aggregating the kilometers of my last runs since a certain date (which is definitely longer gone than 1 week). Any thoughts here?

My watch is freezing constantly after the update. During activities, and multiple times during the day. I made a factory reset, hard reset, soft reset. Nothing helps, and all of the languages disappeared. It was hungarian before, now i can only choose english. A hotfix would be good, because the watch is unusable at this point.

Today I had the first ever freeze, so I'll try to describe here everything to see if matches with another people's problems... There's a long time that I don't run listening to music, but today I did (and the watch freeze)...

I use the FR 645M in Portuguese, FW 6.20 I made a 10km run listening to a Spotify playlist. I connected my Jaybird X3 to the watch and I had no problems due to all the run... No freezes, no audio cutoffs, everything was fine... After the run I stopped the watch and saved the activity, turn the headphone off and the watch returns to the watch faces that I use from Connect IQ... On the elevator almost close to my apartment I pressed the UP bottom to see the BatteryMetter widget and BOOM... The watch freezes... I arrived at home and my iPhone 8 was at the living room as the Wi-Fi router... Then I heard ny iPhone alert saying that the activity was uploaded... I don't know if it was via Wi-Fi or via Bluetooth (I think that it was via BT)... I pressed the LIGHT bottom and could access the menu ring and select Turn off... so I pressed BACK and the watch keep freezed.... So I made a reset (pressing the LIGHT bottom for 15 sec) and the watch returns to work... So as this was the first time that this happened to me and the only new think I did was connecting a BT headphone and listening to music maybe is this the problem? Everybody that is freezing was listening to music during the activity? Another interesting point was that I lost 23% battery in 50 min run listening to music... the same amount of battery that i am losing on same time run not listening to music =/

My watch with its regular freezes after saving an activity is the non-music version.

My watch also did freeze after saving an activity. But i found out that after saving if I used the back button to get to the watch face it didn't freeze. If I choose OK and hit the enter button it did freeze.

You are right. Today I tried to reproduce yesterday's freeze, so I made a 50 min run listening to music, etc... After all I pressed the START bottom to stop the watch, click DOWN and START, so it started to saving the activity... I didn't press any bottom during that "post activity physio summary" then press DOWN and START do return to watch face... At screen face I pressed the UP bottom to see the BatteryMetter widget and the watch didn't freeze this time... So the only difference between today and yesterday was the fact that this time I was far away from my home so no Wi-Fi or BT connectivity close to my watch... Battery drain from 61% to 37%... Well sorry for all this details but i am trying to help to detect what makes the watch freezes...

I tried that and indeed it didn't freeze, although it was intermittent for me, maybe every third activity resulted in a freeze. I'll keep using that method & see what happens. Good find! 

Contacted Garmin Support, provided the files and was added to open development ticket.

They didn't just ask to replace the watch Please keep us in the loop.