Aikido has never failed me - my Aikido has failed me.
Luckily that's hapended only in the dojo.
My student was a boxer - I said hit me - he did. A beautiful taisabaki, unfortunately lousy ma ai.
I had that happen to me when I trained Pentjak Silat. Except it was an MMA/prison guard. And I didn't even get a chance to move my feet before his cross nailed me. I didn't even know HOW he hit me, just that he did.