Tax504 and box 13 check when pension withholdings present

We have multiple pension plans and identified them all in box 14R of the tax form print parameters. We ran TAX504 and TAX910 and have a handful of employees that had pension deductions in 2021 but box 13 doesn't have an X in it. The X is present for most employees in those same plans, but not all. Am trying to determine what would cause the differences.