How to make the DFF on the project transfer Redwood page mandatory

Summary:

We are trying to make the DFF mandatory on the project transfer Redwood page mandatory, we had tried using the business validation rules as If DFF Null, the rule is firing even if the DFF is populated.

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Version (include the version you are using, if applicable):

26C

Code Snippet (add any code snippets that support your topic, if applicable):

Rule Condition

Rule still fires even after the DFF is populated.