Has anyone else had an issue with tax calculations on non periodic payments since the installation of the January tax table update?

We have a client, that had used these types of payments for retro pay for a number of years, and always added that non-periodic earning to the employees pay tab to be included on the same cheque for a pay run.

It used to calculate taxes properly until the January tax table update.  After the installation the same earning added to a taxable employee record no longer calculates the Federal and procincial taxes.