No lock option in CodeForces!

I have participated in around 4 contests on CodeForces as of now! I understand that to be able to hack solutions during the post - contest hacking phase, I need to lock at least one of my correct submissions but I never get to see the lock button in the “problems” page!

Is there anyone else who’s facing the same problem? Kindly help me out!

You don’t need to lock in the post-contest hacking phase. The lock option is there to hack the solutions during the contest.