0.9.2c - Cannot build clay pit

Although all resources are available, the game does not seem to recognize the building site as a clay pit. When trying to place it there, the message “Invalid building placement” appears.
Here is the link to my savegame (expires in 7 days) → Savegame

Are you trying to place a regular clay pit on a deep deposit?

Yes, the error was sitting in front of the screen - sorry. Message can be deleted