CXone Studio ASSIGN and IF logic not triggering for null checks

Trying to branch logic in a CXone Studio snippet based on a REST response. If the payload is null, I want to skip the next action. My current setup uses an ASSIGN to parse the JSON, then an IF to check if the field exists. The IF always evaluates to false even when the data is clearly missing. Here is the snippet structure:

  • ASSIGN: response_data = JSON.parse(body)
  • IF: response_data.customer_id == null

The flow ignores the null condition. Any ideas why the comparison fails?