I asked Gennadiy to give you a detailed response, since I don't know exactly. I just know that the algorithm is off and that people see less time on their save slots than they actually spent playing the game - I also asked Axecidentally to confirm and he did, since I was surprised about his 10h playthrough time (since Maximilian Dood played 6h on his stream and they barely completed Act1, so people finishing all 3 acts and 100% the game first time through in 10 hours seems highly unlikely), he told me in PM he thinks it felt more like 14 or so hours (Quote: " It sure does feel like it. Looking back at my playtime these two past days I'd say I should have a minimum of 14h to be honest. ").thomasmahler
Repeating my question from earlier(sorry if you've seen it already), would you mind sharing what was not counting towards the play time counter? Could give us a better idea what to expect
But anyway, this should be fixed with the Day1 patch.