Thanks for the bug report.
Unfortunately, I was unable to reproduce the problem.
Here's a video:
https://www.dropbox.com/s/2dlj5rpd4j7xw … s.mp4?dl=0
I tried to generate one or multiple terrains, and change various settings, but the problem still does not appear.
Perhaps there is some additional condition for this problem to happen?!

They are still in the folder they where generated from, but not linked anymore.

As there is no smart way to re-link 64 textures without having to do a lot of manual 'looking at texture file and figure out which map slice it belongs to'...I Regenerate the textures. Another couple of hours of wait.

Same thing happens. Great.

Have managed to have the textures stick once so far, seemingly on a fluke. Even if the textures are linked on Save, and seen when re-opening a scene, dropping the link and loading back the Scene again, after not having saved it with the de-linked, doesn't work either.

Is this how it is supposed to work?