Plugin interferes with default WooCommerce checkout

I have a website that uses a Virtual Wallet plugin for Rewards mechanics. In the checkout page where we summarize the order to customers, we noted that the Total Amount is not correct. The total amount of the order in the Checkout page does not include the deduction from the rewards plugin. Eg, my cart total is $1000 and I used $100 discount. The total should show $900 but now the cart total in checkout page reflects $1000 still. I disabled this plugin and managed to get it working accurate. Please advise if there’s anything we can do to resolve this issue.