Problems with terrain

hey guys , first time here. Im currently developing a 3rd person adventure game kinda like zelda. I ran into an issue where if i modify the terrain (sculpting) and then i hit play , the game starts but i have no terrain. it’s as if the terrain dissapeared or got moved somewhere else. Here’s a picture of how it is and then how it becomes after some modify.Any help would be great. Thnx in advance!!!

And your sure there isnt any thing to make it invisible like the checkbox to see if visible or a blueprint to make invisible?

yup , nothing that can make it invisible