That sounds like the gamma setting is off for one of the maps - find the property with the map (probably Base colour) in the Surfaces pane, click on the mini thumbnail to the left, and from the menu select Image Editor - that should show the current gamma value. Make sure both sleeves use the same value (and use the same value as the body). if a mismatch is the issue please report it as a bug, assuming you have checked there is no update for the product.