Unbilled Revenue: Tips 1: 020 (EBW) Update group not entered in billing document &1

Symptoms:

1. Simulated bill is billed successfully AND
2. Simulated bill data not found in Step 5 AND
3. Reversal of simulated bill data is found in Step 5

Reasons:
SAP is expecting Update Group is populated when comes to simulation for Unbilled Revenue (Even if "Initial Update Group Is Allowed" is set to 'X')

Solutions:
Unbilled Revenue: Prerequisites 2: Update Group Determination