Map Editor: Edit overmap does not regenerate actual terrain

[jeremy7986]

Describe the bug

Using Edit overmap in the Map Editor fails to change or regenerate the actual terrain.
Rotating works, and the terrain ID on the overmap updates successfully, but the physical map itself remains unchanged. It should regenerate the terrain to reflect the newly assigned overmap ID.

Steps To Reproduce

Open the in-game Map Editor.
Choose Edit overmap and change the terrain of a specific map tile.
Check the overmap (Notice the ID updates correctly).
Check the actual map location (Notice the terrain is not updated/regenerated).

Screenshots

Versions and configuration

Nightly 2026-08-15

Additional context

No response