Failing "Develop players using club's youth system"... (Youth Academy Only Save)

Thank you for the save file and information. We will investigate further. 

I think this happens if you did not introduce any new developed players this season specifically, since they ignore all the youth introduced during previous years.

So, you can have full 11 of your own, but they "won't count" them if they weren't introduced during the season in question. It can become an issue long term when your team is already built up and you don't really have space for several new talents without disrupting the current team.

Thanks for the theory, we will pass this to our team.

I've noticed something very similar. I was wondering if it was to do with the agreed playing time being the basis of the assessment for this vision, rather than the actual game time you give to the youth players. I tend to minimise agreed playing time as much as possible, so, for example, I have a youth player who's a Future Prospect who I'm using like a Regular Starter. Just an idea. In any case, there's clearly something dodgy about how this Club Vision is programmed.