Disappointing, hoping the blocking volumes would help
The Z plane height -
Hmmm the build grid is limited in size, the players cannot build above 22272 units, I forgot to put the name of the poster who tested that out.
Not sure about how far below, there was another post who did create a crater in the middle of the map, I can’t remember how deep it was, but the player would instantly die there, indicating an auto kill zone at some depth incase a player falls through the map I’d say.
There are currently X and Y limits to the build grid as well, unless they’ve been increased.
But to answer the question, it’s possible. I wonder if they fixed the need for a gridplane yet ???
I would try it at a multiple of 384, -4992 or just remove it and see if building still works.
The distance fx, I mean’t the islands off in the distance and the portion of the ocean outside the waterzone. Was raving on too much and only wondering about the stuff that isn’t in a minimap and how does the engine know this
Waterzone, cool, there is another aspect, where the inner ocean and outer ocean meet at the waterzone, there is a definite line. Ocean and Waterzone extents should be incread until that line blends into distance
Re - Waterbodies, yes they are seperate assets oceans and lakes,
but considering just the ocean’s spline, it has no ocean inside it. this area of no ocean should be stretched around the map so the other waterbodies, lakes, swimming pools and rivers (except for the last node) have no ocean under them.
Now the bug reporters onto it, hopefully the minimap, indicators and marker issues get a look into,
That post, March 2023, that’s around the time UEFN was released, that first post was probably from beta testing, the bug statis is still awaiting validation and not closed. There have been more recent posts about this…
OK I just found the post with Epic Staff, who give the minimap a radius of 61000 at the time of the post May 2023,
Bit disappointing, but I guess the only course is to focus on the map controllers
OK, so looking at the Map Controllers, it could be a settings issue
Using nine map controllers as you have
Give them all priority 100
Uncheck the Activate Automatically
Check the Activate on Trigger
If that fails,
priority 1000 
uncheck activate automatically
uncheck activate on trigger
place down some volume devices the same size as map controller zones
use the map controllers, Activate for Player function with the volume devices On Player Enter Zone
and Deactivate for Player with the On Player Exit Zone
Do this for all nine zones.
If it fails by direct function event, then its more likely the map controllers need more fixing so they can handle an island this big
+1 vote