Non recoverable tax incorrectly added to disribution totals in AP??

I don't understand why a Nonrecoverable Tax is being calculated calculated when I process a purchase invoice in the Invoice workbench?

Invoice total = 119, which includes 19% VAT.

In AP, when I calculate tax, it calculates the correct VAT amount. The Detail Tax lines are all correct.

Invoice workbench - "All Distributions": The Disribution Total adds the amount of the nonrecoverable Tax. ????

Line 1 - Item = 100.00

Line 2 - Recoverable tax = 19

Line 3 - Nonrecoverable Tax = 19

Distribution total = 138

The Recovery rate for Recoverable tax = 100 and the Recovery rate for Nonrecoverable tax = 0, but the distribtion total equals 138 and I would expect it to total 119. I would also expect the Nonrecoverable tax to equal zero.