Markers only show when you’re close to the ground.
Not sure when this happened, I think it was in DF (probably with the introduction of Dragon Riding) but it is very annoying.
The whole point of the Minimap is to indicate where things are if you’re not aware of the exist location.
But now you basically need to know where the thing is and almost land on it before it shows up. Completely overriding its purpose.
And it’s not the same height for all items. Mailboxes seem to show up when you’re still quite high. Flightmasters show up when you are basically touching them.
I have a text file on my desktop with Co-ords for Flightmasters I use regularly so I can find them as the minimap is no longer fit for purpose.