Latin Tax Exception in AR not getting picked up in OM

We are on 12.1.3 and use Brazilian Localization .

In AR under Latin Tax Engine, some exceptions have been defined by item origin.In OM when we click on calculate tax on the SO line, these exceptions are not getting picked up and taxes(can be seen by clicking view tax details) calculated as per regualar tax rates which is incorrect.If this SO line is interfaced to AR and invoice generated there , the Invoice has the correct tax information and we can see the exceptions getting picked up there.Has anyone seen this issue and help us identify the root cause?