Missing Game History

So, more recently than not, I've been playing matches, and for some reason, some of the aren't being recorded, like showing up in match history. I've looked on 3rd party websites, like na.op.gg and lolnexus.com, and using just the usual match history in the league client. I can't find these "missing" matches anywhere. I think there is some sort of bug, but I'm not sure. Could someone please look into this?