Have you found that when you applied the map the lines are ticked as taxed but the rate is 0%?
This is most likely due to this supplier having incorrect default settings. To check go to the Suppliers, select the supplier then select Edit. If it's 'Default Tax Code' says 'No GST', 'GST Free' or similar, then please remove it and leave this field blank. Then refresh the page & apply the map.
This field is best left blank to allow the maps to work correctly, as we will use your 2 default company tax rates you've set. Only in special circumstances would you need to select a different default tax code.
If after making these changes the problem still occurs, then please check that your company's default Tax Rates you've ticked are correct. You can check this in by selecting Edit next to Tax Rates. You must select one Default Tax and one Default Tax Free
You must select one Default Tax and one Default Tax Free
Your tax rates are defined in two separate columns. Be sure to select one from each column to enable the default tax/tax free rates on your account.
For example, in the screenshot example below, we have a column for Default Tax and then another for Default Tax Free. Click the relevant code for the relevant column to your company.