Also you trained inside defense which trains more slowly than other skills. Just because you have achieved 48 minutes with a player and set the training doesn't mean they will pop but if they don't they will become closer to the pop.
Think of it like an RPG game your character needs 100 xp to level up. This weeks training in outside defence on one player may give you 80 towards it, so they still need another 20 to see a pop on the roster page. Another one of your players may have already had 40 towards the next level so the 80 will put them over the 100 xp barrier and you will see a pop.
Fat Curry