Vi ult problems

I have been playing Vi jungle for a long time now, but i have just recently noticed that sometimes Vi ult gets cancelled but still goes on full cool down. Just my last game this happened to me twice. First time the enemy team was taking baron i go in and click ult on blitz, but blitz instantly dies from AP ezreal ult before i even move an inch to ult blitz, and my ult went on full cool down even though my ult didn't go off. I could have gotten an epic quad kill but i died because my ult did go off. Then later that game i clicked vi ult on ziggs, but Jhin's fourth shot killed ziggs before i even moved a millimeter with vi ult, but my ult went on full cool down. Is this a gameplay bug? or is Vi ult supposed to go on full cool down without doing any dmg or even moving???