Non-Taxable allowance showing as taxable on payslip

Hi All

Has anyone seen an issue where a non-taxable allowance is created manually for many employees, but one employee it is moved to the taxable allowances and the PAYG calculated incorrectly?

Removing and re-adding the allowance to the pay corrects the issue (if caught before finalising).  It has happened over multiple pays (same allowance), but there is no issue with the allowance table or pay table except that the figure is moved to the taxable allowance total in the pay table.  No corruptions found to be the cause.

Thanks all.

Michelle