I'm gonna need more info.
Try making a new project and write down what exactly you do.
Okay I did the same thing but it worked, I think I might know what it was. I make the project folder, add wall and floor textures and place down the player, then test it. However, I think the texture I was using was too high resolution. I grabbed a wood texture off google to test but didnt even think the game might not like it, so I used minecraft textures and it worked this time.