Terrain has a strange red X that is not documented anywhere

Bug Reports Engine Bugs
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#1

For some reason my terrain icon has a red X and I can’t find any information online except for this one post about it:
image

Except I’ve never used the material generator as far as I’m aware.
Removing everything and setting as many defaults as I can back to normal has not fixed it.

Here’s the place file so you can see for your self:
Terrain is mad.rbxl (80.5 KB)

#2

This is a side effect of the ever-confusing decision to make Terrain a BasePart.

You can see that it has a MaterialVariant from the command bar:

  > =workspace.Terrain.MaterialVariant
  NewAsphalt

What you might have done by accident is shift-select a bunch of parts to apply a material variant, and included Terrain in that as well.

If you type:

workspace.Terrain.MaterialVariant = ""

The (X) goes away.