Salesforce CPQ Percent of Total discount does not populate on renewals

There are 2 steps to address this use case:

1. Create a Price Rule
2. Test/Validate

Create a Price Rule to Populate Additional Discount % on Percent of Total Renewal Quote Lines

1. Navigate to the Price Rules tab
2. Create a new Price Rule
   1. Price Rule Name: PoT Renewal Discount %
   2. Evaluation Scope: Calculator
   3. Conditions Met: All
   4. Active: True
   5. Calculator Evaluation Event: On Calculate
3. Navigate to the Price Condition object in Setup and add the following values to the picklist field named SBQQ__Field__c if they are not already there:
   1. SBQQ__Type__c
   2. SBQQ__SubscriptionPricing__c
   3. SBQQ__RenewedSubscription__c
4. Create a Price Condition so the Price Rule only fires on Renewal Quotes
   1. Object: Quote
   2. Field: SBQQ__Type__c
   3. Operator: equals
   4. Filter Type: Value
   5. Filter Value: Renewal
5. Create a Price Condition so the Price Rule only fires on Percent of Total Quote Lines
   1. Object: Quote Line
   2. Field: SBQQ__SubscriptionPricing__c
   3. Operator: equals
   4. Filter Type: Value
   5. Filter Value: Percent of Total
6. Create a Price Condition so the Price Rule only fires on Quote Lines with a Renewed Subscription
   1. Object: Quote Line
   2. Field: SBQQ__RenewedSubscription__c
   3. Operator: not equals
   4. Filter Type: Value
7. Create a Price Action to populate Additional Discount %
   1. Target Object: Quote Line
   2. Target Field: Discount (%)
   3. Formula: SBQQ__RenewedSubscription__r.SBQQ__Discount__c 

Test/Validate

1. Create an opportunity on an account. Note: you must create a new Account record if one does not already exist in your org.
2. Create a new Quote related to the Opportunity created in Step 1
   1. Primary: True
   2. ​Start Date: Any date
   3. ​Subscription Term: 12
3. Click Edit Lines and Click Add Products
4. Select a Percent of Total subscription product and a covered product included in the Percent of Total calculation
5. Populate the Additional Discount % for the Percent of Total product quote line and Save the Quote
6. Navigate to the opportunity and check the Contracted checkbox
7. Navigate to the newly created contract and check the Renewal Quoted and Renewal Forecast checkboxes
8. Navigate to the contract's renewal opportunity and observe that the Percent of Total opportunity product and quote line pricing matches the original quote line and Additional Discount % matches the original quote line's Additional Discount %. 

Considerations:

1. The above use case applies to Sales Cloud Contracts, if you are using the Service Cloud for Salesforce CPQ integration package the Price Action formula should reference the quote line's Renewed Contract Line instead of Renewed Subscription. 
2. The above use case relies on Additional Discount % being populated on the original quote line. If users populate Additional Discount (Amt), the Price Action should be adjusted to target Additional Discount (Amt) and the formula should reference the subscription's Additional Discount Amount. If users use both Additional Discount % and Additional Discount (Amt), you can use two Price Rules to ensure that Additional Discount is always populated on the Percent of Total's renewal quote line.