Where did heat acclimation go

It's working on my 530.

830. Gone too 

It's winter here, but I saw a 5% heat "acclimation" message about a week ago on my 830

Last summer I had no problem with it. This year after my first ride in heat (avg temp was 30 degrees) I realized that something was wrong with it. I use an 530 for recording rides, but I am almost fully sure that it works like 830.

More details in a Fenix 6 thread: https://forums.garmin.com/outdoor-recreation/outdoor-recreation/f/fenix-6-series/230759/heat-acclimation-for-fenix-6-and-edge-830/1634878#1634878

As you can see I checked what I could and my last post there confirms that I rode in a heat (see Weather widget data) and the weather station also thought it was hot enough.

Since then I found out there is another place to check weather data related to Heat Acclimation.

I also checked the weather info in GC, placed on the map (top-right) and it shows 31.1 degrees for the yesterday ride.

My 530 shows 1% Heat Acclimation under the Training Status page in My Stats.

I get weather but heat acclimation is gone everywhere. There was a firmware update a couple weeks ago

You mean, 9.75? It was exactly 3 months ago. But certainly I could not exclude it as a reason behind.

Brain cramp. There was a map update not firmware

I'm continuing to get heat acclimation on my 530.  Just providing another data point.

Just to separate cases, is your 530 your primary/only  device, or do you also have a second device, a watch? Just to be sure that physio True Up does not cause any malfunction,