Tactix 7, fw 20.22, Polar H10.
Yesterday, I dutifully did my DSW: A 43 minute base run. The max HR recorded by the watch for the activity was 145 bpm. After I stopped and saved the activity, an unexpected "New Threshold Detected" briefly appeared for a few seconds and then disappeared, without me pressing any buttons. I then went to the Performance widget to see what the new LTHR was, and it said 164 bpm and also at a pace I never hit! I never went above 145 bpm.
Today, the watch still shows that LTHR/pace was updated yesterday, so it stuck. I thought well that sucks, but surely it will update on the next Threshold run.
Enter today's DSW: Threshold run of 15:00 @ 161bpm. I intentionally went over target and averaged ~ 166bpm for around 10 minutes, and peaked to 174bpm in the final 30 seconds. Yet to my frustration, the watch did not detect a new LTHR. Seems it is stuck, so I need Garmin help to resolve.
This is clearly a bug, and before posting this I saw this user reporting the same issue, 5 months ago!
https://forums.garmin.com/outdoor-recreation/outdoor-recreation/f/fenix-7-series/399008/the-new-running-lactate-threshold-only-detected-on-slow-runs/1876463
