Need a benefit certification FF when coverage amount increased

I have configured a Supplemental Spouse Plan with explicit coverage elections ($10,000 to $250,000) and no plan options. During New Hire enrollment, employees can enroll up to the Guaranteed Issue (GI) amount without requiring Evidence of Insurability (EOI). However, if an employee later increases their coverage during a life event, EOI should be triggered.

I have created and attached a benefits certification formula of type Enrollment Certification Required to the plan to trigger EOI only when the elected coverage amount increases, but EOI is not being generated when the coverage changes.

Has anyone successfully configured EOI to trigger only on coverage increases for a supplemental plan without options? Are there any additional configuration steps or considerations beyond the certification formula that I should verify?