Forerunner 965 - Lactate Threshold not Updating - 21.19

Hi. 
I am having the exact same issue. My Last update was when I did a manual lactate threshold test in October. I also wear a chest strap HRM I do a large portion of my running with, and I have not have an "update" since my manual test. 
With the new update, the ability to do the manual test has now gone, therefore I am unsure how to follow the threshold update. Like you, I have the auto detection on in settings for Max HR, Threshold and FTP, so not sure what I'm missing. 

If you get to the bottom of it, would appreciate you letting me know :) 

I have the exact same issue. Despite multiple runs and trail runs since the update at different effort levels, I haven’t received a single update yet.

I'm experiencing the same exact situation on the same 21.19 firmware but on a FR255

Same issue here.

Same here, no update on endurance score, race predictor, and LT after recent firmware update.

The feature is working well for me on my Epix Gen 2.

Note that I did a complete factory reset when I installed the firmware that got rid of the threshold test and I didn't do a restore. The reset should re-initiaze the models on the watch. I would guess a restore wouldn't copy back old models, but only settings, so you could try a backup-reset-restore process. Or you could call Garmin Support.

Since 21.19 I saw a MaxHR update but no Threshold update, even after today's Threshold run does as part of my Marathon plan...it shows as manual in the settings (152bpm). The average HR during the Threshold intervals is 151.33 so maybe it doesn't need to be updated ;-)
However I was told to run at 4/km and the app shows 152/4:08 so it's a bit inconsistent

Factory reset or hard reset didn't work for me.

Same here!