I posted that the sync was confusing but the post disappeared, presumably by the moderators for some reason.
I have now narrowed down what the sync issue was that was making me think it was confusing with Explore App and Fenix 5.
When you establish the Location in Explore App it syncs all good with Fenix 5.
When you establish the location in the Fenix 5, it syncs to Explore App and Web OK, but does NOT sync back to the Fenix 5.
Yes I have allocated the Fenix 5 locations to a Collection. And I have tried including it in My First Collection and the required Collection, still no worky.