This book had just installed the casino when I began playing there. They always checked for BJs. I got 21 with 5 cards or so and the dealer got 20 with 3 cards or so and mine was graded as a loser. I didn't make a big stink because it was only $10 and I was up $5k in sports. But this is one of the books advertised on top and has A+ rating. I'v never played again there since.
Could you have added wrong ( had 19) ?
A hand history is possible to get,usually.
If both are 21, it's a push.
They'd probably reward you for finding a flaw ?