Issues with spritebatch + custom effect on Windows + DirectX

[Creadude]

And wouldn’t you know it, as soon as I post this, I find my issue. Apologies!

XNA Effect port not working

Yes… the basic thing you are missing is that there is always a vertex shader. In this case I assume you are rendering with SpriteBatch. When you provide SpriteBatch with a custom effect with only a pixel shader, the vertex shader from the stock SpriteBatch effect is used. You can see here how the pixel shader for the stock SpriteBatch effect is defined: https://github.com/mono/MonoGame/blob/develop/MonoGame.Framework/Graphics/Effect/Resources/SpriteEffect.fx#L41 … you can see how it takes …