Cancellation of trades at closing time

Few days back I had a Zinc June 2020 buy position. At around 11.20pm it was trading at 159.10-159.15. At that time I put squareoff order at 11.20pm for 159.65. At 11.30pm, my order got cancelled and Zerodha’s Kite mobile app showed LTP to be 159.15 or something around this price. But next day when I opened the app I saw that closing price on earlier day was 159.95. So, I want to ask why my order was not executed? Did Zerodha cancel my order and hence it got removed from the exchange’s log? Almost every day I see the closing price not matching with LTP when checked on next day. And as such my trades not getting executed is observed multiple times by me. Can someone explain me why is this happening?

@Siva

Why is my query not answered by @Zerodha or any other better knowledgeable person?

Hi,Close price will be calculated based on the last 30 minute average traded price except expiry day. So LTP and close will not match mostly.

I think this answers my query. Thank you!!