Bug or intended? - Interrupted items have cooldown
Interrupting item use such as teleport scroll by abilities such as UB's grasp will not only just cancel the cast, but also induce cooldown time (very long for items usually). I don't think this is intended because of the fact that casting teleport scrolls to a friendly building when the building is destroyed will just cancel the cast without incurring cooldown penalty.
Why would there be a cooldown if the cast is unsuccessful?