Have you tried other additions to your huel yet? I’ve found making it in a blender & adding coffee, sugar free syrup, fruit, coffee, honey, maple syrup etc all improve the taste greatly as well as leaving it overnight in the fridge as you are already doing.
Many on here are fans of the myprotein flavdrops, haven’t tried them personally but I got loads of ideas from this thread… Hope that helps a bit! How do you flavour your Huel?