Locking phone with apps... general usage question

Hi,

A user contacted me to ask about an exercise app I have that he says doesn't lock, even when lock is applied.

The simple reason that might be is that the device I had been using (735xt) simply didn't have the sophistication to do that so I've never had reason to suspect that there was a feature I hadn't built for.

Now I am on a newer watch (Fenix 6x Sapphire) I can theoretically test locking behaviour, but I couldn't see anything that matched what the user was talking about. There was an auto-lock during activity, but I'm not quite sure what that does, why or how.

Certainly, it didn't seem to affect my app when I ran it with auto-lock during activity set.

Is this just standard behaviour that I can do nothing about? (EG: Does auto-lock only affect Garmin activities rather than app activities?)

Or is there a level of functionality that I have yet to discover?

Is there a way around this?

Now that I have the new device to test on, simply pointing me in the right direction would be useful.

Thanks,

G