Cannot update the cart page details with some custom discounts and reward point sums

Question

In cart page I'm trying to update the cart total and subtotal values based on my custom discount and reward points.
While select the discount and reward points the total has changed and show the values in few seconds, after some api's (Like /V1/carts/mine/totals-information) call automatically and the discount amount are disabled and the total amount revert to old values.