The iliotibial tract or iliotibial band is a longitudinal fibrous reinforcement of the fascia lata. The action of the muscles associated with the ITB (tensor fasciae latae and some fibers of gluteus maximus) flex, extend, abduct, and laterally and medially rotate the hip. The ITB contributes to lateral knee stabilization.
Important to note here these are the actions of the muscles attached TO the ITB!
The IT Band is fascia not muscle. Fascia is actually by design quite resistant to stretching; it is meant to transfer load.
Because the IT band itself can't be stretched, it's likely time to change up your stretching and foam rolling routine. Rolling up and down the length of your IT band isn't going to have any effect on the IT band itself long term.