ER OASDI Tax Not Taken on taxable benefit deduction w zero earning paycheck

Payroll NA.

We processed a deduction adjustment ("refund" a $1-After Tax and "add" that $1 as Nontaxable). There are other Taxable benefit deductions on the check, totaled to a taxable gross amount, but there's zero earning. After the calc, Net pay = $1 refunded. Federal payroll tax EE/ER was calculated but was put under "Tax Not Taken" (total EE,ER tax > $1 net pay)

We want to ask that while it makes sense to not collect OASDI EE tax due to not having enough net pay and put it under "Tax Not Taken", but why OASDI ER was also put under "Tax Not Taken"? Does this behavior work as the program intended? or is it due to process/configuration error?