Most apparel items have different color options you can select as you reach certain levels (I'm not sure about the ones you purchase through the Pro Shop though as I've never bought anything from there). Make sure when you select the pants, check below the item info box and see if multiple color options are available - if so maybe you've inadvertently selected Olive instead of white.
I've also seen a discussion on Discord where several people are reporting issues with Puma pants showing one color at the waistband and then another starting at the hips, so WGT might be messing around with the coding to try to resolve that issue and it's causing your described problem.