Changing the FX Rate on a GRN produces a Total Tax Amount even though Quantity is 0.

Changing the FX Rate on a GRN produces a Total Tax Amount even though Quantity is 0.

Steps:

Fresh demo data
Load PO 100517
Change the line tax rate to be GST IN. Save.
Change the status to Sent
Load GRN form,
Create a new GRN for creditor 5290
Add PO 100517 to the grn
Change the tax rate on the grid to be GST In
Right click on grid and tick "Use Custom Columns"
Right click on grid and "Mange Columns" - tick to make FXRate column visible
Note that "Total Tax Amount" on the grid is 0 - this is because quantity is 0.
Change the FX rate to be 1.3 - NOTE "Total Tax Amount" gets a value. This is incorrect, it should be 0 because Quantity is 0.