Configure Audience Filtering to return 'Unknown'

Audience Filtering for 'Is not true' currently does not return 'Unknown'.

Case: Mandatory GDPR Audience Attribute = ‘unknown’ when the free account is created but not finalised due to onboarding not being completed.
Accounts are created using the email address after step 1 of the registration process and before Audience attributes (password, name, questions) are shown.

Issue: Filtering for ‘Is not true’ only looks for ‘false’.

Segmenting using a filter for ‘unknown’ gives clarity on those who have 'not opted-in' to compulsory GDPR attributes and need actioning.