The Issue
The Terrain Editor button on the Home tab and View tab in Studio will appear selected/clicked as though the window is open despite being closed. This only happens after opening a place if the Terrain editor was initially closed. This happens 100% of the time when opening Studio and when switching between places in Studio.
I’m uncertain when this had started occurring since the bug doesn’t break anything and can be very easily missed. The editor can still open and close like normal. You’ll just need to click the button twice the first time in order to open it.