EXP Share got permanently knocked off

I was facing one of the DexNav battlers, one of the Thief guys, and his pokemon used Knock Off on my Typhlosion. Not a big problem normally, but I got a little disturbed when I saw no item in his listing on the Pokemon selection screen. I ignored it, but I finally went to take his EXP Share off him… and its no where to be seen? None of my Pokemon have it, its not back in my items, and I can’t imagine anywhere else it would have gone. I can easily just go buy another on the Black Market, but I wasn’t sure if this was a known bug?

EDIT: However it got used on me again and did not knock off the Magnet my pokemon was holding, so it isn’t applicable for every item and/or all the time