Match ID :40014327
Very early into this game Ivy's "Watcher's Covenant" and "Stone Form" stop working and would only let me activate after getting hit by certain abilities. I'm not sure what caused this to happen but nothing I did in game fixed it.
The way you fix this bug is by exiting and re-entering the game. It happens on all heroes since the first mina update. it seems to happen to some people very infrequently and some other seem to get it every single match