Problems with Analytics/Reports

Hi there,
I’m using WOOCS on my website with Brazilian real as the base currency and USD as the other currency option but I have noticed that sometimes the WOOCS Order Info field has a currency conversion rate and other times it doesn’t, and I also noticed that because the order does not register a currency conversion rate it messes up the analytics because the values keep changing according to the rate on the day I look at the analytics instead of the date when the order was placed.
Is there any way to fix this and make sure all orders will have a currency conversion rate registered to them?

Thank you so much.