Customer or Product Specific Tax not picked up in AR nor AP Invoice

 I have set up a Tax Regime /Flow in a Vision Environment and this is working fine. The default tax codes are picked up normally (High VAT) and if I have set up a supplier or customer or AR memo line with another Tax Rate (Tax Classification), this is working fine.

However, in a new environment (re-implementation, not an upgrade), the default Tax Rate is picked up and the Tax Rate at Memo Line or Customer or Supplier level is visible, but simply ignored.
I have compared the set up in both environments and they look the same. However, I must be overlooking something.