Non-host player cannot see host's map marker at all

(Note that this is a different issue from MCPE-25907, which I also reported)

Problem: Host and non-host have inconsistent or incorrect map marker visibility on non-cloned maps.

Steps to Reproduce:

1. Start an online world and invite another player
2. Equip both players with locator maps
3. Have each player use and look at their locator maps

Expected Behavior:

(According to Wiki)
A) If the maps are clones of each other, both players should be able to see both markers
B) If the maps are not clones of each other, each player should see their own marker only

Actual Behavior:

A) Unknown if the maps are clones of each other; I need to test this
B) If the maps are not clones, the host can see both markers (subject to MCPE-25907), but the non-host cannot see the host's marker (which, if I'm reading the Wiki correctly, is intended behavior for non-cloned maps)