Merge fields are not replaced by record values, but are output as they are.

Check that the merge field format is correct.

• Check if the format of the merge field is {!Object API Name.Field API Name}.
• Check if the object name and field name are correct.
• Check if "!" is not missing.
• Check if there are no unnecessary spaces.

Child Object

If the reference field is a custom field, append "__r" at the end of the child relationship name.

How to find the merge field and childrelation names

Instruction manual

Template Common Settings

Output Reference Object (Parent) Field