Lactate Threshold is always "Manual Entry"

Try setting LT for running activities as basis for your heart rate zones. That's what I did to get rid of "manual entry". Unfortunately there doesn't seem to be another solution yet. 

I already use LT for my HR zones.  Today I noticed that the LT calculation works and updates until you sync with the Garmin app, which then changes it to manual...Considering that my efforts are based on my LT pace, it does screw with my relative efforts that I use to overview my training/stress.  Definitely makes me less satisfied with my large purchase of the Fenix 6X Pro. 

I went in Garmin Connect and set up running zones as a % of LTHR.  My normal HR zones are also based on % LTHR.

Nothing changes on the watch, but maybe it will pick it up next time.  I'll update here in a week when I have another tempo workout.

I have had this issue for quite some time and couldn't figure out a fix.  I also had an issue where the auto detected or guided test lactate threshold was ridiculously low (73bpm).  I ended up contacting support and they replaced my watch.  My new watch now shows the detected lactate threshold vs the manual entry.  It's still showing 73bpm from the last guided test since I haven't done a new guided test or ran enough with the new watch yet for it to detect a new threshold but at least it's showing the detected values instead of a manual one.

In case you haven't noticed you can also see the lactate threshold and if it was detected from an event (it will show the date of the event) or if it's using a manual entry from the VO2 Max widget screen.

I have a hard time believing the manual vs auto detect issue is a hardware one but by getting a new watch it somehow stopped connect from over writing the auto detected entries on the watch with a manual one.

I agree you can see the LTHR and pace under the Vo2Max widget.

Mine worked before but has presented the above issue over the last month, so definitely a software issue. 

I also know it works since it correctly showed my detected LTHR and pace this morning before I connected to Garmin Connect, at which point it was replaced by "Manual Entry."  I have updated my run HR zones in Garmin connect (a feature separate from normal HR zones) (they were already set on my watch too as a % of LT). 

I am looking forward to the bug fix.

I wonder if removing the watch from connect, performing a factory reset, then adding the watch back would be of any help.

It sounds like others are experiencing this issue, so I'd guess not.  A factory reset is always no fun and makes a lot of work for the user for setting things back up, e.g. music and custom settings (which I have plenty of) and removing all distance/pace records.  I won't do this until Garmin confirms it as a fix.

New Fenix 6s Pro/Sapph. - LTHR was auto detecting just fine, then stopped after some software updates.

1. Disconnected/Unpaired the watch from Garmin Connect
2. Did a factory reset on the watch, re-synced everything back up
3. LTHR Auto Detect started working again on the first run after reset.

Sport Specific LTHR is OFF.

Then I read this post, start looking at my LTHR again, and here are all the readings where I think I can get it from:

1. Watch > Performance Widget > LT Manual Entry > 168
2. Watch > Settings > User Profile > Heart Rate > LTHR > 168
3. Garmin Connect iOS > Performance > Lactate Threshold > 168
4. Garmin Connect iOS > Device > User Settings > Heart Rate Zones > LT > 167

I had different readings before the factory reset like above...so I would say factory reset is not the solution. There's an ongoing bug if all these readings (should) be the same and the watch (should not) say Manual Entry when it's in Auto Detect mode and there's never a Manual Entry by the user.

The same for me. The only thing we can do, by now, is editing lactate on the phone when we had a new one on the watch.