Total Learning Minutes calculation

Hello - 

I have been 'assigning' students to work on Khan for 30 minutes on Mondays. I taught them how to find out how many learning minutes they have logged so they can monitor the time themselves - I also showed them that the minutes are calculated based on actual work time - and that Khan knows if they go to another tab or aren't actually working in Khan.

One of my students just messaged me that he did do 30 minutes, but it only shows 2 minutes. He said he did the work on his cell phone. Is it possible that because he was working on his cell phone, his true learning minutes were not captured? I told him I don't think it matters on what platform he was working; it should still calculate it properly, but said I would seek official confirmation from you.

Thank you!

Katelyn