Okay, I tried to just recreate the landscape. This time setting the correct scale from the start, thinking maybe that way the regions would behave.
This time, initially I saw no regions at all in the minimap. Okay, weird, but whatever. Then after capturing the minimap texture, the regions appeared and now everything is great.
So yeah, if you call starting over a solution, then yeah, I suppose this is it.
I still have no idea what caused it. Presumable scaling and or moving the landscape after creation, but I thought you were supposed to be able to do that…
I’ll leave this unsolved for now, but will mark this as the solution later if no better (not having to start over with a new landscape) solutions get posted.