We sometimes get a steady and constant breeze here near the sea and I have picked the right days in the past to do various wind tests. A friend of mine in Perranporth has a perfect field with a sea view and with my wind speed meter I could confirm an almost constant wind speed. I haven't ever seen any difference in the deflection of a pellet in left and right winds of the same speed. So if you are experiencing that, then Rob's suggestion would be all I could think of.
I could have saved myself a lot of time and effort by using Chairgun, but getting outside with the gun is far more fun.