For whatever reason on OpenGL terrain normal mapping is always enabled regardless if the terrain has it disabled, and a majority of converted maps don't have their normals set up properly.
The only current fix would be to provide a blank normal map by following these steps:
Download the zip attached below and extract it.
Place blank_NRM.dds in the terrain's zip file.
Open the terrain's page file in a text editor (e.g. Bajatrack-page-0-0.otc)
Change the normal map texture to blank_NRM.dds, like so: