No stress numbers after workout

This seems to be normal behaviour even if you wear a chest strap as this data is always being read from the optical sensor on your wrist.  After all my tests the stress widget only displays up to my high zone 2 range in which case it reads 100% stress at this range (125bmp).  Anything higher than that and it will not display the value no matter how still I remain.  
Do not worry though as all the other metrics like lactate threshold, VO2 Max, recovery time, etc all look to compute fine even though this stress metric isn’t quite right. For reference my heart rate can get up to 180 bpm, and often have it higher than 170 for over 10 min or so when racing.

Here is my investigation on the accuracy of the body battery metric if you have time to read:

https://forums.garmin.com/sports-fitness/running-multisport/f/forerunner-745/240304/body-battery-accuracy-increased-with-chest-strap

Oh sorry guys, seems like we have a misunderstanding here. I meant, "Right after the workouts ends" and the watch starts to use the wrist optical sensor again, I get heart rate readings, but no stress readings. It takes between 30 and an hour or so to get the first stress readings. You see that gap in the daily view, right after each workout.

In the last two or three days I've seen the same thing on my brand new 745. The stress widget stops being detected. I still don't know if this depends on doing an activity or not. And the same for me: sometimes I just have to activate the widget or sometimes I have to restart my watch. 

I'm a little disappointed. What’s wrong?

Usually your heart rate is too high.  I have discovered when I do an activity after about 100bpm the Stress widget no longer works.  Then when you are at a lower heart rate it kicks in again