Parts of terrain going invisible after building the game and changing ingame resolution

Hello! I added a ingame settings for my game. In Editor everything works fine.But when i build the game, run it, and change resolution or quality, some parts of terrain vanish.I dont use standard unity terrain shader, i use 'Standard (specular)' because it allows holes (i know it looks worse). Here is a screen

The render queque of the custom material used as shader is 2100, i think. So its pretty standard.I previously had modified some of build graphics settings, so i think it might cause the problem.Have anyone of you experienced this issue?