I noticed a minor bug that occurs when replacing terrain using the built-in terrain replacer tool.
When replacing terrain using this feature, the output will display “Starting Sea Level” and “Sea Level Complete: X Seconds” rather than the expected “Starting Terrain Replacement” and “Terrain Replacement Complete: X Seconds”, or something similar.
I noticed this the first time I used the tool, and have noticed it occurring ever since.
This happens 100% of the time AFAIK.
Repro:
Studio → Home → Editor (Terrain) → Edit → Replace
Note that this is only noticeable with the output open.