Hello again. So I HAD moss in my map but I removed it because it made the wall behind it invisible. Does anyone know how to fix this? Thanks 

the patch/mesh should be about 1-2 units away from the wall. since the material is a blend type, it trys to blend with the texture under it, but in the end gives up

the patch/mesh should be about 1-2 units away from the wall. since the material is a blend type, it trys to blend with the texture under it, but in the end gives up

Lightmap it and make it non-colliding.

if its in radiant the reason it renders texture transparent and makes it hard to construct level around it is because the moss and the texture UNDER the moss are both blend, so if you had a dirt under it, the real culprit is the dirt.

Try put a NON-blend texture under the moss and it will look just fine in radiant, hope this helps (if invisible in game then the other answers with lightmap SHIFT+L or 0.25 unit offset will work) just assumed you might have the problem in radiant not ingame just to cover all bases.