Incorrect exchange rate picks in Purchase order

Hi Support,

we have faced a rather strange issue with one of our clients using sage 2018 PU2. The currency rates table is updated daily with exchange rates. However when  a PO is raised for a foreign  currency vendors, a different rate is picked and the conversion is done using that rate. If rate entered is 0.30, the PO rates tab picks 0.12 for some reason.

no changes have been  made to the setup.