WHTax is not calculated for foreign currency invoices -- Urgent

Hi All,

Need you assistance on following situation .

1) We have an invoice Inv123 for URUGUAY with USD currency so it's a foreign currency invoice cause local currency is URY. 

2) We have multiple Witholding tax rate setup of different types.

         a) Flat Rate  : WH1

          b) Amount Range : WH2

Issue :-

We are unable to calculate WHTAx of Amount Range (WH2) for foreign currency invoices like USD and invoice is going on 'Witholding Tax' hold.

Addition to that , We are able to calculate WHTAx of flat rate(WH1) on foreign currency invoice (USD) including URY.

Please advise that is it possible to calculate the amount range WHTax rate on foreign currency invoices or is there  any setup that is missing which I should check.