Terrain texture won't update on one section all others fine

First of I was trying to use “Arid Desert” from the market place, had issues with it in 4.8 and 4.9 - tho 4.9 isn’t supported, one of the Terrain blend Materials causes a shader error as it references too many textures, before I had learnt this I applied it to a terrain and when I replaced it with an other material, one area dose not update to the new Material. I have built the map. reload the map, restarted UE4, restart the PC the material doesn’t update, what is the correct way to fix this issue? I have also assume this is bug - if this is in the wrong category my apogees.








Ok, I was able to replace the Material of that one section with the terrain manage tool and selecting it and changing it twice, first time it reset on re-select the terrain section, but after changing it the second time I saved before re-selecting and it, then I re-select and my changes had this time been saved.