Not able to create approval rule based on contact type / relationship (Family and Emergency Contact)

Summary:

Our client has a requirement to create approval rule for family member based on relationship type as some of the type will determine the benefit and impacted payroll.

Content (please ensure you mask any confidential information):

Created approval rule with (Proposed Person ContactRelationship.result.contactTypeMeaning == "Child") . However, when creating the transaction it goes to error saying "An attribute in the Approval rule has a null value." and upon further checking in the log, null value was mapped in the attribute which should not be the case as it was provided during the transaction.

Reference:

Rule Attribute Value Map :

Task.payload.Proposed Person ContactRelationship.result.contactTypeMeaning:{}