A default value for a field may not be set on the creation of a new record, even provided in the field definition
In many cases, the reason for that is an onchange method that is resetting the value for the field.
Steps that can help in resolving the issue:
- Identify the method that is causing the issue by searching by the field’s name, and seeing where the field’s value is reset.
- Try to understand the current logic and how your change will affect it.
- Override the method using
super and apply your custom logic