as you can see in the following video, vi's ult gets stopped under weird circumstances(?) not entirely sure why.
theArtifacts1 votesVi got stunned by Jhin and then minion blocked. Doesn't look like a bug, just unfortunate circumstances.
UK Chriscolumbo3 votesVi ult can't be stopped though.
theArtifacts1 votes[{quoted}](name=Chris in Colour,realm=EUW,application-id=LqLKtMpN,discussion-id=VO1PEkZE,comment-id=00000000,timestamp=2016-11-01T20:41:33.727+0000)
Vi ult can't be stopped though.
That's the bug then. Just read the tool tip. Vi should not be able to be stunned once she clicks her ult.