Edit: This hopefully has been solved. In your heart rate settings, there is another subfolder 'sport heart rate'. When I adjusted my lthr there, a message popped up informing me that automatic adjustment has been turned off.
I had a training 4 weeks ago where the hr sensor recorded a flat line of 192 bpm for 3/4 of the session.
My real hrmax is 171 and yes, it's really that low.
The watch then informed me right after that training, that it automatically corrected my threshold to an insanely high heartrate.
I deleted said training and replaced it with a fit file in which I stripped the heartrate data off with fit tools, which did nothing to correct anything within the garmin app.
Yesterday, the watch told me that it set a new threshold hr of 152, which still is 11 bpm too high.
And the thing is, I have threshold hr set to manual input in the settings for cycling and running, and there my hr sits at the right 141 bpm.
But the garmin app seems to ignore that and has some non-adjustable internal value because it thinks it knows better, and so I get only bollocks for my recovery values and training status ever since.
What to do now, and what to do if it happens again?