LTHR detection off

I’ve noticed that some of my friends have like red bubbles with HR changes, and I don’t. They also got their threshold filled without doing it, and it’s changing as garmin changes. Should I delete or do something to get my LTHR detection working? I tried to delete the value I wrote on the LTHR manually, but I can’t.

And this is mine

This 180 was written by me, not detected

Thanks in advance and sorry for this newbie “problem”