All twist drills are "self cleaning" in that the spiral of the flute is intended to lift the drilling chips (granules) out of the bore the same way a screw conveyor moves powdered and granulated materials.
If the material is sticky it will not move as freely along the flute spirals and new chips will jam up into the chips ahead of them in the bore and gum the bit up eventually jamming it as it expands against the bore wall.
The deeper you go the more this will be accentuated.
Back the bit up a little more frequently and competely withdraw it from the hole more often as you drill deeper.
Heat of drilling will also become more of a problem and cause the wood granules to become sticky the deeper you drill, and the hotter they get the more the problem will be accentuated, maybe directing a blow gun in the bore while drilling will help as it would help cool the bit, but adjusting the speed and feed rate then checking the bit temperature (it should get warm, not hot) when you pull it out to clear the chips would be better.
Deep holes in gummy aluminum present a similar problem and there are bits with a slower twist rate made to make chip removal easier and allow deeper drilling (in metal a coolant is usually used as well, which really isn't practical in wood).
Try pulling the bit out more often and wiping it with a wet cloth to cool it down some and see if that helps.
