Morning,
Only on day 2 of Huel but noticed yesterday when I sniffed my shaker that the contents smelt slightly plastic or somewhat like chlorine. I put it down to a new shaker but my older protein shakers contain the smell scent when loaded with Huel.
Just thought I’d ask to make sure I don’t have a dodgy batch 
More likely the water than the Huel 
Assuming you’re using tap water to mix yours - the water in my area can sometimes taste more chlorinated because our water comes from underground water supply reservoirs, to which I think they occasionally add a tiny bit of chlorine.
Try a new shaker and just use bottled water (cheapo stuff from the supermarket will do) and see if the smell persists.
If you’re already using bottled water, then you’re much more posh than me, and in that case it may be worth trying a different brand of water?
Assuming it is tap water that is the problem then keeping water in the fridge overnight or using a water filter jug are worth trying. Some people say Huel mixed and kept in the fridge over night is better, I wonder if that has the same effect on chlorine. I’d also make sure you clean the shaker straight after using it, don’t store it with the lid on and keep it out of direct sunlight.
So I tried bottled water in my shake then still left in fridge overnight. Same result; so it still smells like a swimming pool.
My shakers are both very clean, never get any issues when having protein shakes from them.
Might try the next bag of huel tonight and see how that comes out in the morning, otherwise I assume I’ll just have to accept it and carry on.