TiledMap effect (pixel shader) is not working

Your Effect needs to implement this interface: https://github.com/craftworkgames/MonoGame.Extended/blob/541e162887745d43669298d687100f564b9644cd/src/dotnet/MonoGame.Extended.Tiled/Renderers/TiledMapEffect.cs#L6

Also, I don’t see a vertex shader in your shader program. The vertex shader is important as it transforms the positions of the tiles from model space all the way to clip space.