It’s possible that you are somehow overloading the tibialis posterior and not the bigger calf muscles, perhaps because it is tighter?  The DU are faster and more intensive than any other of the jumping exercises so perhaps it illuminates the area when the other activities don’t?

The tib posterior inserts into a lot of places including the navicular and metatarsals 2 through 4.  Have you smashed the bottom of your feet as well?  Are you a pronator or do you have any level of collapse in your arches?  You could try doing your DU’s in a blocked position (feet right together) and see if it still hurts.