Many times homeowners forget that a tree was once a living thing and not some type of uniform widget. Each tree is an individual. As a consequence, there is always a degree of physical variation in the amount of pitch contained in each tree. Pitch is a gooey, sticky, resinous substance composed of a mixture of rosin, turpentine, and other volatiles produced in pine trees and other conifers.
When pitch "bleeds" or oozes out of wood it primarily occurs around knots, although sap bleeding can appear in other areas of the log. Oozing pitch will penetrate right through a wood stain causing discoloration of the stain. Its amber color turns white when it dries.
Often discoloration caused by dried pitch is mistaken as a color failure of the wood stain itself because the cause of the discoloration is not understood. Bleeding pitch can be dissolved with turpentine or mineral spirits. If it's hardened it can be sanded to the bare wood beneath. A hot air gun can also help to soften partially hardened resin and once melted the pitch can be wiped with one of the recommended solvents.
After the pitch is cleaned, the area can be touched up with the same color stain. However, there is no guarantee that it will not occur again. In fact, if it's a real active area that contains a large pitch pocket, expect to clean it periodically.