It's normal that there are delays in cashing out or accepting new live bets. Most bookies I have tested in the past, have delays from 6-8 seconds in Europe. Asian bookies are apparently 2-4 seconds but I have never played on such sites. This can sometimes increase even up to 10 seconds. 7 seconds is within the normal timeframe. There is a delay between the events at the venue and the picture you see on TV or live stream. That's why bookies have these in-built delays to prevent people from sitting at the venue and making bets as soon as an event happened. It's normal.
True and on the contrary, as far my experience from Asian Bookies it's more than that actually, it boils down to 10 seconds.
But definitely this bookies will have this in-built delays as you have said.
And not sure how long is the OP betting that this might be the first time that he had experience this kind of "delays", apparently. I know that feeling because I have been there before, done that, but it is what it is.