I've been doing some testing around this.
Currently CR has 10% cashback for Under Armour. There is also a 20% off coupon that I can use with Under Amour (found on CR's website).
If I activate CR, I can't use the coupon but I can use the coupon if CR isn't activated.
Has it always been like this?
Seems to work fine for me? Where are you falling into difficulties? Do you mean that you can't apply a coupon code when clicking through CR within the cart (as in the code box is missing) or it doesn't activate on the item?
It doesn't activate the discount applied by the code
This doesn't sound like a CR issue, sounds like the coupon doesn't apply on the product you're trying to purchase.
I tried it on one colour for one product and just assumed it worked for all other colours of the same product. Turns out it doesn't…
I guess the coupon says its for almost everything. I just find it weird that the coupon applies to one colourway but not another colourway for shoes
CR has permitted coupons, otherwise you will use the coupon and get no cash back (or reduced in some cases).