Fiddle sometimes gets locked out of flashing even after ult channel completes

Hey, so ever since the ninja update which I think occurred in patch 6.15 (the one that made it impossible to flash DURING the ult channel), occasionally after completing the channel Fiddle will get locked out of flashing for like a half a second or so. It kinda sucks, especially when you set up the ult from farther away thinking that you will be able to flash immediately. I still have no idea what causes it and it just seems to happen randomly.