Forgetting that an individual generally can't claim a personal casualty loss in 2020? I think there's an exception for certain disasters.

Generally, you may deduct casualty and theft losses relating to your home, household items, and vehicles on your federal income tax return if the loss is caused by a federally declared disaster declared by the President

Problem solved.  It's a federal disaster area so a personal casualty can be taken.  However, with a personal casualty, when the insurance reimbursement is larger than the adjusted basis of the property the reduction in FMV is irrelevant, even if this reduction is lower than the adjusted basis.  Because of this, Proconnect simply leaves the before and after FMV off of form 4684.