It is not working because of the new cookie policy by safari which blocks cross domain cookie management in the iframe. You will have to try out offsite order execution.
You can refer to this example, the only difference will be exchange, that is NFO. The tradingsymbol anyways you can get it form the instruments master dump.
A strange behavior that today I have placed a lot of small orders a total of 69 and do you think it is failing just because of the #of orders are too many? Could you please try to reproduce this?
You can pass the "product" parameter along with the button. The parameters are documented here -- https://kite.trade/docs/connect/v1/#offsite-order-execution