I believe your problem emanated from the fact that you didn't read stakes casino rules.
I personally do not believe this to be a bug, you said that while the casino was still counting down on 7 seconds cash out limit, the score for the game you bet on changed from 10:10 to 10:11, now, you didn't tell us if this change was in your favor or against you. If the change was against you, I think it's normal that cash out would be declined by the game provider.
Exactly. If the game happened to 10-11 and you were to withdraw it 10-10 then definitely you (OP) supposed to understand the simple calculation, and from what you (OP) said, the game did not on your favour. Casino games are tricky, Op you would have withdraw or redeem the bet when it was in 10-9 which was nice but your planned to win big make you to loss the bet. All the same, I am sorry for the lost. Next time be smart enough to deal with all these things. And probably the channels you used placing the bet or monitoring was also the caused of the skipping the second of the time to 11 instead of 10. And I believed you used mobile phone to placed the bet. Tennis game is a game of luck.