I’m going to guess that the color of the liquid material is quite dark. For Raytraced and Rhino Render since Rhino 7 you need to take the color you want, but then make it light. Typically increasing the value, sometimes desaturate - or a combination of.
Think of the colors as filters. If you put in black in a glass material then you won’t get any light filtering through, since black filters out everything.
See for instance this reply in another topic: