How do I fix my materials when they just turn grey when applied

Whenever I use a material it just turns into the default grey checkered material and it doesn’t apply itself to the object. I’ve tried using starter materials because I thought it was a problem importing textures, but it did the same for them too, but strangely enough, some of them work and some don’t

it may just be taking awhile to compile the shaders. some materials can take quite awhile due to being complex and some may not even show they are compiling on occasion. personally ive had issues with the paragon characters taking ages (several mins) to compile.

Even in 2021 im facing the same issue!!
using UE4.26.1 update

same, i created a landscape material the blends with height and it just wont apply to my landscape while every other megascans material works fine, its just the ones ive custom created dont work

My guess is you added in manually other files from other projects and something is broken just a theory and i think its fairly valid as i’m dealing with it right now as well with items being in a create a project not add too project if i find a work around ill post it here