The river under the tavern disappears when opening build menu. Also the cave. Close the build menu and it returns.
http://prntscr.com/hl30do
1.117.0ed8f2ac41 (08.12.2017 8:32), NorMags (104209), zz1, en_US, WIN 17,0,0,188, Windows 7, MSIE 11.0, 1920x940, DirectX9 (Baseline Extended) (336 MB VRAM)