@Vladimir-A-Shekhovtsov Lingvist is trying to follow the conception of a learning day that ends at 3 am, which is a great idea in theory, but thanks to the laid-back implementation, not all of the subsystems follow that concept, that leads to all sorts of troubles especially for those switching between web and mobile. There is not a lot you can do accept observing, adjusting and tolerating. Earlier doing a card from a mobile client after midnight used to start a new learning day or make word counter stuck. I guess you have try and see for yourself.
P.S. the idea behind this is that the words you've learned before midnight are still fresh and do not magically settle down after 12 am. Lingivst guys assumed that even if you are a night owl, you would go to bed before 3 am, thus have a break and a new learning day will start just after that.