GL.Clear not using GL.Viewport setting in OpenGL

Hi everyone, I’m working on a tile based game, and I’m trying to delete certain tiles in a level by using the GL.Clear method
in combination with GL.Viewport. This works great on Windows and DirectX, but when I force the editor
to use OpenGL, the Clear method doesn’t seem to care about the Viewport setting and it clears the whole texture.
Am I missing something here?

This is what the code looks like in a nutshell:

RenderTexture.active = myRenderTexture;
			
GL.PushMatrix();
GL.LoadPixelMatrix(0,myRenderTexture.width,myRenderTexture.height,0);
			
GL.Viewport( new Rect(0,0,48,48) );
GL.Clear( true, true, Color.clear );
				
GL.PopMatrix();
RenderTexture.active = null;

I guess what I’m looking for is the equivalent of the OpenGL glScissor method!