We recently made this update to apply discounts on manual orders faster.
From your Shopify dashboard, create an order.
Then apply to a customer (that has discount tags), products they'd like to order and save.
Once saved, it will be a draft order. Click more actions and then Apply Wholesale Pricing Discount. It will apply the discount tag for the customer to the order.
Only % off discounts and individual pricing will work with manual orders.
Here is a demo video.