New problems with presense detection?

After working without problems for 2 years ST has stopped detecting the presense of any of the 3 family members. Started by one stopping, then two, and now all three.

As presense detection is used in many of my automations this has become a major issue.

So have some questions:

  1. Did something change recently with either ST or iOS that is causing this?

  2. Are others experiencing this lately?

  3. Any suggestions on fixing this?

There are a few threads relating to this issue. Have a look around.