"Claim victory" feature not working always

As you see from the time stamps, I waited 2,5 mins for a game that is mate in 1 for me. My opponent left the game (according to the grey dot besides my opponent's name), but the game didn't end until the time go down to 0. I read somewhere that if a player leaves the game, you can claim a victory in 20 secs or something... Obviously, in this case, this did not happen. I don't know if this is a system bug or something but I mention it here in any case.

Maybe there are some criteria.

The disconnect timeout is 2 minutes... so I'm unsure what happened here.

I wonder if the opponent logged back into to see if you left and logged back out again thus creating another 2 minute timer. Possibly a bug though.

I've noticed this happens if you just refresh your page you can claim it. Sometimes takes multiple refreshes.