Yes!! I have this same problem too! I think it is the exact same players who play via the app who can join games and get in without the host's consent. I happened to try and look up the head to head stats with someone I play against a lot, and there was no head to head. This is also a player who, when they click on my posted game, the game starts immediately without me agreeing to start it. I had a hunch that this might be a pattern, and sure enough... all of the players who can join my game without the 'game accept' box appearing have no head to head history vs. me. I'm sure we are not alone with this issue.
Anyone know why my stats for average word score and average game score never change? I've written to the developer at least four times over the years, but they only answered once to tell me they'd get back to me. That was a year or more ago. Everything else updates: highest word score, highest game score, longest bingo, overall score; it's only the word and game averages that never do.