This is how you Generate Nanite LDS & Save.
I just updated to 5.3 from 5.2 and there seems to be a bug where, when saving, it wants to generate Nanite for the entire Landscape prior to any saving, even if you only try to save a single Proxy at a time.
So to correct for this, we want to load in only small sections of the LDS at a time.
To do this:
1.) Turn Off Nanite for your Landscape & Save
2.) Select All Proxies and turn ON “Is Spatially Loaded” & Save
3.) Unload your entire level - in the World Partition Editor, highlight everything & Unload. (Window–> World Partition → World Partition Editor)
4.) RELOAD the level - Go to your level in the Content browser and double-click to reload
Upon reloading, none of your LDS should be visible.
5.) Select your Landscape Actor and Turn ON Nanite - Optionally turn on Nanite Skirt, which helps hide seams.
6.) Go back into the World Partition Editor, select a small region and load it.
7.) Select your Landscape Proxies and “Build Data”
8.) After Nanite Builds, Save All
Repeat 6-8 until entire LDS is Nanite & Saved
Optional:
Afterwards, select all proxies and turn off “Is Spatially Loaded”
Good luck!